Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
References Next
Reprinted from American Journal of Respiratory and Critical Care Medicine , Vol 211/Issue 5, Baraldi F, et al, Blood Eosinophil Count Stability in Chronic Obstructive Pulmonary Disease and the Eosinophilic Exacerbator Phenotype, pp870-872, Copyright 2025, with permission from Oxford University Press.
*Cells/μL (N=100). Patient groups defined by stable-state BEC across 4 annual visits: Persistent (≥3 visits with BEC ≥300 cells/μL), Intermittent (1–2 visits with BEC ≥300 cells/μL), and Never (0 visits with BEC ≥300 cells/μL). The time frame for V1 is within 18 months before V2, while V2, V3, and V4 are each separated by 12 months. 2
BEC, blood eosinophil count; V, visit.
Reprinted from , Vol 211/Issue 5, Baraldi F, et al, Blood Eosinophil Count Stability in Chronic Obstructive Pulmonary Disease and the Eosinophilic Exacerbator Phenotype, pp870-872, Copyright 2025, with permission from Oxford University Press.
BEC, blood eosinophil count; V, visit.
Many patients with COPD continue to exacerbate, suggesting an underlying driver of disease 1
A single measurement may not reveal a patient’s full inflammatory pattern over time 1
35% 40% 65% 60%
5%
7%
50%
50%
93% 65% 95% 85%
35%
15%
Longitudinal Year-over-Year Fluctuation of Blood Eosinophil Status (Over 4 Years) 2
Data from a prospective longitudinal COPD cohort, tracking eosinophil variability and exacerbation type
Exacerbation Type by Stable BEC Pathway 2
of patients exhibited evidence of type 2 inflammation (BEC ≥300 cells/µL) over 4 years fluctuate intermittently
of patients maintain persistently high BEC over 4 years
18%
29%
47%
BEC <300*
BEC ≥300*
Year 1 Year 2 Year 3 Year 4
Blood eosinophils are a key biomarker for the early identification of underlying type 2 inflammation 1
High BEC correlates with increased exacerbation rates 2
Patients with exacerbations characterized by BEC ≥300 cells/µL experience a significantly higher annual exacerbation rate (4.1 vs 3.0; P =0.03)
Eosinophilic risk exists even in “Never” patients 2
26% of patients with consistently low BEC had at least one exacerbation visit with BEC ≥300 cells/µL
100%
0%
50%
Persistent (Always ≥300) Intermittent (Fluctuates) Never (Always <300)
51
49 89 26
74 11
Patients (%)
Non-eosinophilic
exacerbations (BEC <300 cells/µL)
Eosinophilic
exacerbations (BEC ≥300 cells/µL)
Blood Eosinophil Counts Vary Both Within a Day and Over Longer Time Periods
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
References Back
Characterizing eosinophil patterns alongside evaluation of medical history, comorbidities, and other type 2 biomarkers can help identify patients with evidence of underlying type 2 inflammation, supporting a deeper understanding of COPD biology and disease heterogeneity 1 Clinical Implication
Absent type 2
inflammation
Likely some degree of
type 2 inflammation, especially if BECs are at the
higher end of the range
Moderate-to-high likelihood of type 2
inflammation
Very high likelihood of
type 2 inflammation
Predominantly
Low
BECs <100 cells/µL
Intermediate
At least 1 BEC 100 to 300 cells/µL AND no BECs >300 cells/µL
Intermittently
High
At least 1 BEC ≥300 cells/µL,
but majority of BECs
<300 cells/µL
Predominantly
High
Majority of BECs
≥300 cells/µL
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
Identifying Patterns of Eosinophil Variability 1
Low
BEC <100 cells/µL
Absent type 2 inflammation
High
BEC ≥300 cells/µL
Confirmed type 2 inflammation
Intermediate
BEC 100 to 300 cells/µL
More likely that significant type 2 inflammation
is present at higher counts within this range
BECs over multiple clinical visits
Repeat Measurements (if available)
One BEC Snapshot
A Single Measurement
Biological COPD-Related Medication Environmental Technical
Key Factors Influencing Eosinophil Counts 1 *
Reprinted from American Journal of Respiratory and Critical Care Medicine , Vol 211/Issue 5, Baraldi F, et al, Blood Eosinophil Count Stability in Chronic Obstructive Pulmonary Disease and the Eosinophilic Exacerbator Phenotype, pp870-872, Copyright 2025, with permission from Oxford University Press.
*Cells/μL (N=100). Patient groups defined by stable-state BEC across 4 annual visits: Persistent (≥3 visits with BEC ≥300 cells/μL), Intermittent (1–2 visits with BEC ≥300 cells/μL), and Never (0 visits with BEC ≥300 cells/μL). The time frame for V1 is within 18 months before V2, while V2, V3, and V4 are each separated by 12 months. 2
BEC, blood eosinophil count; V, visit.
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
Many patients with COPD continue to exacerbate, suggesting an underlying driver of disease 1
A single measurement may not reveal a patient’s full inflammatory pattern over time 1
35% 40% 65% 60%
5%
7%
50%
50%
93% 65% 95% 85%
35%
15%
Longitudinal Year-over-Year Fluctuation of Blood Eosinophil Status (Over 4 Years) 2
Data from a prospective longitudinal COPD cohort, tracking eosinophil variability and exacerbation type
Exacerbation Type by Stable BEC Pathway 2
of patients exhibited evidence of type 2 inflammation (BEC ≥300 cells/µL) over 4 years fluctuate intermittently
of patients maintain persistently high BEC over 4 years
18%
29%
47%
BEC <300*
BEC ≥300*
Year 1 Year 2 Year 3 Year 4
Blood eosinophils are a key biomarker for the early identification of underlying type 2 inflammation 1
High BEC correlates with increased exacerbation rates 2
Patients with exacerbations characterized by BEC ≥300 cells/µL experience a significantly higher annual exacerbation rate (4.1 vs 3.0; P =0.03)
Eosinophilic risk exists even in “Never” patients 2
26% of patients with consistently low BEC had at least one exacerbation visit with BEC ≥300 cells/µL
100%
0%
50%
Persistent (Always ≥300) Intermittent (Fluctuates) Never (Always <300)
51
49 89 26
74 11
Patients (%)
Non-eosinophilic
exacerbations (BEC <300 cells/µL)
Eosinophilic
exacerbations (BEC ≥300 cells/µL)
Blood Eosinophil Counts Vary Both Within a Day and Over Longer Time Periods
References Next
The Persistent Pathway
In this group, 89% of patients experienced at least one exacerbation with BEC ≥300 cells/µL during the study, indicating a strong association with type 2 inflammation 2
FEV 1 , forced expiratory volume in 1 second.
Clinical Note
Baseline exacerbation rates and FEV 1 % predicted were similar across groups, suggesting that these measures alone may not reflect underlying inflammatory patterns 2
Reprinted from American Journal of Respiratory and Critical Care Medicine , Vol 211/Issue 5, Baraldi F, et al, Blood Eosinophil Count Stability in Chronic Obstructive Pulmonary Disease and the Eosinophilic Exacerbator Phenotype, pp870-872, Copyright 2025, with permission from Oxford University Press.
*Cells/μL (N=100). Patient groups defined by stable-state BEC across 4 annual visits: Persistent (≥3 visits with BEC ≥300 cells/μL), Intermittent (1–2 visits with BEC ≥300 cells/μL), and Never (0 visits with BEC ≥300 cells/μL). The time frame for V1 is within 18 months before V2, while V2, V3, and V4 are each separated by 12 months. 2
BEC, blood eosinophil count; V, visit.
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
Many patients with COPD continue to exacerbate, suggesting an underlying driver of disease 1
A single measurement may not reveal a patient’s full inflammatory pattern over time 1
35% 40% 65% 60%
5%
7%
50%
50%
93% 65% 95% 85%
35%
15%
Longitudinal Year-over-Year Fluctuation of Blood Eosinophil Status (Over 4 Years) 2
Data from a prospective longitudinal COPD cohort, tracking eosinophil variability and exacerbation type
Exacerbation Type by Stable BEC Pathway 2
of patients exhibited evidence of type 2 inflammation (BEC ≥300 cells/µL) over 4 years fluctuate intermittently
of patients maintain persistently high BEC over 4 years
18%
29%
47%
BEC <300*
BEC ≥300*
Year 1 Year 2 Year 3 Year 4
Blood eosinophils are a key biomarker for the early identification of underlying type 2 inflammation 1
High BEC correlates with increased exacerbation rates 2
Patients with exacerbations characterized by BEC ≥300 cells/µL experience a significantly higher annual exacerbation rate (4.1 vs 3.0; P =0.03)
Eosinophilic risk exists even in “Never” patients 2
26% of patients with consistently low BEC had at least one exacerbation visit with BEC ≥300 cells/µL
100%
0%
50%
Persistent (Always ≥300) Intermittent (Fluctuates) Never (Always <300)
51
49 89 26
74 11
Patients (%)
Non-eosinophilic
exacerbations (BEC <300 cells/µL)
Eosinophilic
exacerbations (BEC ≥300 cells/µL)
Blood Eosinophil Counts Vary Both Within a Day and Over Longer Time Periods
References Next
The Intermittent Pathway
Despite fluctuating stable-state eosinophil counts, 51% of patients in this group experienced at least one exacerbation with BEC ≥300 cells/µL during the study, indicating active underlying type 2 inflammation 2
BEC, blood eosinophil count.
Clinical Note
These findings suggest that a single BEC measurement may miss up to 29% of patients who demonstrate an eosinophilic phenotype over time 2
Reprinted from American Journal of Respiratory and Critical Care Medicine , Vol 211/Issue 5, Baraldi F, et al, Blood Eosinophil Count Stability in Chronic Obstructive Pulmonary Disease and the Eosinophilic Exacerbator Phenotype, pp870-872, Copyright 2025, with permission from Oxford University Press.
*Cells/μL (N=100). Patient groups defined by stable-state BEC across 4 annual visits: Persistent (≥3 visits with BEC ≥300 cells/μL), Intermittent (1–2 visits with BEC ≥300 cells/μL), and Never (0 visits with BEC ≥300 cells/μL). The time frame for V1 is within 18 months before V2, while V2, V3, and V4 are each separated by 12 months. 2
BEC, blood eosinophil count; V, visit.
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
Many patients with COPD continue to exacerbate, suggesting an underlying driver of disease 1
A single measurement may not reveal a patient’s full inflammatory pattern over time 1
35% 40% 65% 60%
5%
7%
50%
50%
93% 65% 95% 85%
35%
15%
Longitudinal Year-over-Year Fluctuation of Blood Eosinophil Status (Over 4 Years) 2
Data from a prospective longitudinal COPD cohort, tracking eosinophil variability and exacerbation type
Exacerbation Type by Stable BEC Pathway 2
of patients exhibited evidence of type 2 inflammation (BEC ≥300 cells/µL) over 4 years fluctuate intermittently
of patients maintain persistently high BEC over 4 years
18%
29%
47%
BEC <300*
BEC ≥300*
Year 1 Year 2 Year 3 Year 4
Blood eosinophils are a key biomarker for the early identification of underlying type 2 inflammation 1
High BEC correlates with increased exacerbation rates 2
Patients with exacerbations characterized by BEC ≥300 cells/µL experience a significantly higher annual exacerbation rate (4.1 vs 3.0; P =0.03)
Eosinophilic risk exists even in “Never” patients 2
26% of patients with consistently low BEC had at least one exacerbation visit with BEC ≥300 cells/µL
100%
0%
50%
Persistent (Always ≥300) Intermittent (Fluctuates) Never (Always <300)
51
49 89 26
74 11
Patients (%)
Non-eosinophilic
exacerbations (BEC <300 cells/µL)
Eosinophilic
exacerbations (BEC ≥300 cells/µL)
Blood Eosinophil Counts Vary Both Within a Day and Over Longer Time Periods
References Next
The Never Pathway
In this group, 26% of patients experienced at least one exacerbation with BEC ≥300 cells/µL during the study, demonstrating that eosinophilic events can occur even in patients without a documented history of elevated stable-state BECs 2
BEC, blood eosinophil count.
Clinical Note
Stable-state monitoring alone fails to identify eosinophilic risk in the ‘Never’ phenotype, where over a quarter of patients ( 26% ) still experienced at least one exacerbation with BEC ≥300 cells/µL despite having consistently low stable-state BECs across all four annual visits 2
Dynamic Eosinophils: Decoding Variability in COPD
Characterizing eosinophil patterns alongside evaluation of medical history, comorbidities, and other type 2 biomarkers can help identify patients with evidence of underlying type 2 inflammation, supporting a deeper understanding of COPD biology and disease heterogeneity 1 Clinical Implication
Absent type 2
inflammation
Likely some degree of
type 2 inflammation, especially if BECs are at the
higher end of the range
Moderate-to-high likelihood of type 2
inflammation
Very high likelihood of
type 2 inflammation
Predominantly
Low
BECs <100 cells/µL
Intermediate
At least 1 BEC 100 to 300 cells/µL AND no BECs >300 cells/µL
Intermittently
High
At least 1 BEC ≥300 cells/µL,
but majority of BECs
<300 cells/µL
Predominantly
High
Majority of BECs
≥300 cells/µL
Identifying Patterns of Eosinophil Variability 1
Low
BEC <100 cells/µL
Absent type 2 inflammation
High
BEC ≥300 cells/µL
Confirmed type 2 inflammation
Intermediate
BEC 100 to 300 cells/µL
More likely that significant type 2 inflammation
is present at higher counts within this range
BECs over multiple clinical visits
Repeat Measurements (if available)
One BEC Snapshot
A Single Measurement
Biological COPD-Related Medication Environmental Technical
Key Factors Influencing Eosinophil Counts 1 *
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Exploring Eosinophil Fluctuation Patterns 1
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
BEC, blood eosinophil count.
Predominantly Low
This pattern is defined by BECs that consistently remain low (eg, predominantly <100 cells/µL), with only minor, clinically irrelevant fluctuations. It is generally indicative of an absence of underlying type 2 inflammation 1
200
500
0
400
300
100
Intermediate
Tap another BEC pattern above to learn more
Intermittently High Predominantly High Predominantly Low
Minimal fluctuation Increased fluctuation
BEC (cells/µL)
In the low (BEC <100 cells/µL) and intermediate (BEC 100 to 300 cells/µL) range,
expect small fluctuations
If readings are either intermittently or predominently high (BEC ≥300 cells/µL), expect
greater fluctuations between measurements
Exploring Eosinophil Fluctuation Patterns 1
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
BEC, blood eosinophil count.
Intermediate:
Some degree of type 2 inflammation may be present in this range, particularly at higher counts. The ≥150 cells/µL threshold, discussed in some clinical trials, falls within this zone of clinical nuance 1
200
500
0
400
300
100
Intermediate Intermittently High Predominantly High Predominantly Low
Minimal fluctuation Increased fluctuation
BEC (cells/µL)
In the low (BEC <100 cells/µL) and intermediate (BEC 100 to 300 cells/µL) range,
expect small fluctuations
If readings are either intermittently or predominently high (BEC ≥300 cells/µL), expect
gre ter fluctuations between measurements
Tap another BEC pattern above to learn more
Exploring Eosinophil Fluctuation Patterns 1
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
BEC, blood eosinophil count.
Intermittently High:
This group represents an important diagnostic challenge. Data show that relying on a single, one-off measurement can miss up to 29% of patients who would otherwise be defined as having an eosinophilic phenotype when assessed over time 1
200
500
0
400
300
100
Intermediate Intermittently High Predominantly High Predominantly Low
Minimal fluctuation Increased fluctuation
BEC (cells/µL)
In the low (BEC <100 cells/µL) and intermediate (BEC 100 to 300 cells/µL) range,
expect small fluctuations
If readings are either intermittently or predominently high (BEC ≥300 cells/µL), expect
gre ter fluctuations between measurements
Tap another BEC pattern above to learn more
Exploring Eosinophil Fluctuation Patterns 1
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
BEC, blood eosinophil count.
Predominantly High:
This is considered a very high likelihood of type 2 inflammation, demonstrating a strong link between this pattern and the underlying type 2 disease drivers 1
200
500
0
400
300
100
Intermediate Intermittently High Predominantly High Predominantly Low
Minimal fluctuation Increased fluctuation
BEC (cells/µL)
In the low (BEC <100 cells/µL) and intermediate (BEC 100 to 300 cells/µL) range,
expect small fluctuations
If readings are either intermittently or predominently high (BEC ≥300 cells/µL), expect
greater fluctuations between measurements
Tap another BEC pattern above to learn more
Dynamic Eosinophils: Decoding Variability in COPD
Characterizing eosinophil patterns alongside evaluation of medical history, comorbidities, and other type 2 biomarkers can help identify patients with evidence of underlying type 2 inflammation, supporting a deeper understanding of COPD biology and disease heterogeneity 1 Clinical Implication
Absent type 2
inflammation
Likely some degree of
type 2 inflammation, especially if BECs are at the
higher end of the range
Moderate-to-high likelihood of type 2
inflammation
Very high likelihood of
type 2 inflammation
Predominantly
Low
BECs <100 cells/µL
Intermediate
At least 1 BEC 100 to 300 cells/µL AND no BECs >300 cells/µL
Intermittently
High
At least 1 BEC ≥300 cells/µL,
but majority of BECs
<300 cells/µL
Predominantly
High
Majority of BECs
≥300 cells/µL
Identifying Patterns of Eosinophil Variability 1
Low
BEC <100 cells/µL
Absent type 2 inflammation
High
BEC ≥300 cells/µL
Confirmed type 2 inflammation
Intermediate
BEC 100 to 300 cells/µL
More likely that significant type 2 inflammation
is present at higher counts within this range
BECs over multiple clinical visits
Repeat Measurements (if available)
One BEC Snapshot
A Single Measurement
Biological COPD-Related Medication Environmental Technical
Key Factors Influencing Eosinophil Counts 1 *
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Tap to explore
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids ; SABA, short-acting β2 -agonist.
This is the 21-month journey of a 79-year-old female patient
with a history of recurrent COPD exacerbations
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
Month
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
The profile begins with a
BEC of 300 cells/µL, indicating the presence of
type 2 inflammation
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
An early peak in BEC at ~400 cells/µL coincides
with an exacerbation
requiring an ED visit
Month
Post exacerbation, the BEC drops
to near zero. Very low eosinophil
counts may be attributable to
oral corticosteroid use
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Month
An exacerbation occurs, requiring
an ED visit , even with the patient’s BEC in the ‘Intermediate’
range at ~200 cells/µL
The subsequent drop to ~100 cells/µL likely reflects the
suppressive effect of OCS prescribed during the
Month 10 ED visit
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
BEC peaks at ~400 cells/μL,
corresponding to an exacerbation requiring
hospitalization
Month
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
BEC spikes to its highest level (~400 cells/µL), corresponding to an
exacerbation requiring an ED visit
Month
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
The plummet to near zero illustrates
the potential effect of OCS administered during hospitalization
Month
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Diagnosis: COPD
CT Findings: Centrilobular emphysema; no bronchiectasis
History: Ex-smoker with hypertension & coronary artery disease
Key Findings: FEV 1 58% predicted; BMI 19 kg/m²
Status: Recurrent exacerbations (requiring ED visits & hospitalization)
Medications: Various cardiovascular medications; Umeclidinium/vilanterol (LAMA/LABA); Rescue salbutamol (SABA)
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second; LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Tap any graph icon to explore key events, or proceed to the quiz below
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Hospitalization occurred even with an intermediate eosinophil
count (~100 cells/µL)
Month
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second;
LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
This 21-month trajectory shows how COPD can vary over time, illustrating the real-world complexity of COPD
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Predominantly
Low Intermediate Intermittently
High
Predominantly
High
Based on this patient's 21-month journey, which proposed phenotype best describes them? Select one. ?
Month
BEC Fluctuation Over 21 Months 1 *
Illustrative Case:
Case Profile: 79-Year-Old Female
This 21-month trajectory shows how COPD can vary over time, illustrating the real-world complexity of COPD
200
500
0
400
300
100
BEC (cells/µL)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
Not quite. The correct answer
is ‘Intermittently High.’ The key is the repeated fluctuation
above the 300 cells/µL threshold over time
Not quite. The correct answer
is ‘Intermittently High.’ The key is the repeated fluctuation
above the 300 cells/µL threshold over time
Not quite. The correct answer
is ‘Intermittently High.’ The key is the repeated fluctuation
above the 300 cells/µL threshold over time
Correct! The patient’s eosinophil counts fluctuate significantly
over time, with multiple readings
crossing the
300 cells/µL
Predominantly
Low Intermediate Intermittently
High
Predominantly
High
Based on this patient's 21-month journey, which proposed phenotype best describes them? Select one. ?
Month
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
*Illustrative case. Hypothetical patient created for educational purposes.
BMI, body mass index; BEC, blood eosinophil count; CT, computed tomography; ED, emergency department; FEV 1 , forced expiratory volume in 1 second;
LABA, long-acting β 2-agonist; LAMA, long-acting muscarinic antagonist; OCS, oral corticosteroids; SABA, short-acting β2 -agonist.
Dynamic Eosinophils: Decoding Variability in COPD
Characterizing eosinophil patterns alongside evaluation of medical history, comorbidities, and other type 2 biomarkers can help identify patients with evidence of underlying type 2 inflammation, supporting a deeper understanding of COPD biology and disease heterogeneity 1 Clinical Implication
Absent type 2
inflammation
Likely some degree of
type 2 inflammation, especially if BECs are at the
higher end of the range
Moderate-to-high likelihood of type 2
inflammation
Very high likelihood of
type 2 inflammation
Predominantly
Low
BECs <100 cells/µL
Intermediate
At least 1 BEC 100 to 300 cells/µL AND no BECs >300 cells/µL
Intermittently
High
At least 1 BEC ≥300 cells/µL,
but majority of BECs
<300 cells/µL
Predominantly
High
Majority of BECs
≥300 cells/µL
Identifying Patterns of Eosinophil Variability 1
Low
BEC <100 cells/µL
Absent type 2 inflammation
High
BEC ≥300 cells/µL
Confirmed type 2 inflammation
Intermediate
BEC 100 to 300 cells/µL
More likely that significant type 2 inflammation
is present at higher counts within this range
BECs over multiple clinical visits
Repeat Measurements (if available)
One BEC Snapshot
A Single Measurement
Biological COPD-Related Medication Environmental Technical
Key Factors Influencing Eosinophil Counts 1 *
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
*Key factors shown for illustrative purposes; not intended to be comprehensive.
BEC, blood eosinophil count.
References Back
Clinical Context: Factors Influencing Eosinophil Counts 1
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
Age
Sex
Obesity/BMI
Race and ethnicity
Circadian rhythm/
time of day
Biological
Factors
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Clinical Context: Factors Influencing Eosinophil Counts 1
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
COPD diagnosis
Comorbid type 2
disease (asthma, CRSwNP, etc)
Eosinophilic
exacerbations
Bacterial infection
(acute or chronic)
COPD-Related
Factors
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Clinical Context: Factors Influencing Eosinophil Counts 1
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
Atopy/clinical allergy
Parasitic infections
Other eosinophilic/
autoimmune diseases (eg, vasculitis, AD, etc)
Metabolic
disorders (diabetes, hypertension, metabolic syndrome)
Acute severe or
systemic infections
Disease-Related
Factors Other
Than COPD
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Clinical Context: Factors Influencing Eosinophil Counts 1
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
Smoking (general
population)
Seasonal variations
Exercise
Eating
Environmental
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Clinical Context: Factors Influencing Eosinophil Counts 1
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
Lab-to-lab
analysis differences
Single vs repeated
measurements
Time from collection
to analysis
Storage conditions
Technical
Issues
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Figure reprinted from Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
AD, atopic dermatitis; BEC, blood eosinophil count; BMI, body mass index; CRSwNP, chronic rhinosinusitis with nasal polyps; IL, interleukin; NSAID, nonsteroidal anti-inflammatory drug.
Clinical Context: Factors Influencing Eosinophil Counts 1
While eosinophils can be measured in sputum or via bronchoscopy, BECs are the most commonly used method in clinical practice 1
While sputum counts may have a greater predictive value for exacerbation risk, BECs are more easily obtained and reflect the levels of type 2 lung inflammation 1 !
Biological Factors
Elevates Reduces Variable effects Minimal/no effect
Medication
Technical Issues
Environmental
Disease-Related Factors
Other Than COPD
COPD-Related Factors
Hypersensitivity to
drugs (eg, antibiotics, NSAIDs, etc)
Systemic
corticosteroids
Biologics
(IL-5-targeted biologics)
Inhaled
corticosteroids
Biologics
(IL-4/IL-13-targeted biologic)
Medication
Educational content has been developed in collaboration with medical experts. ADVENT is a medical education non-promotional program for healthcare professionals organized by Sanofi and Regeneron.
© 2026 Sanofi and Regeneron Pharmaceuticals, Inc. All Rights Reserved. MAT-US-2609769 - v1.0 – P 09/2026 pulmonology • COPD
Dynamic Eosinophils: Decoding Variability in COPD
References
1. Bafadhel M, et al. Chest. Published online July 25, 2026. doi:10.1016/j.chest.2026.06.060
2. Baraldi F, et al. Am J Respir Crit Care Med. 2025;211:870–872.
Home