Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers: Findings From the PAIVED Study

Ryan Liberg; Kat Schmidt; Christina Schofield; Anuradha Ganesan; Wesley Campbell; David Hrncir; Tahaniyat Lalani; Tyler Warkentien; Katrin Mende; Ana E Markelz; Catherine M Berjohn; Laurie Housel; Jitendrakumar R Modi; Adam Saperstein; Alan Williams; Bruce McClenathan; Christina Spooner; Srihari Seshadri; Ryan C Maves; John H Powers; Robert J O'Connell; Mark P Simons; Simon D Pollett; Christian L Coles; Rhonda E Colombo; Timothy Burgess; Stephanie A Richard

doi:10.1093/ofid/ofaf728

Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers: Findings From the PAIVED Study

Ryan Liberg, Kat Schmidt, Christina Schofield, Anuradha Ganesan, Wesley Campbell, David Hrncir, Tahaniyat Lalani, Tyler Warkentien, Katrin Mende, Ana E Markelz, Catherine M Berjohn, Laurie Housel, Jitendrakumar R Modi, Adam Saperstein, Alan Williams, Bruce McClenathan, Christina Spooner, Srihari Seshadri, Ryan C Maves, John H PowersRobert J O'Connell, Mark P Simons, Simon D Pollett, Christian L Coles, Rhonda E Colombo, Timothy Burgess, Stephanie A Richard

Research output: Contribution to journal › Article › peer-review

Abstract

BACKGROUND: The Pragmatic Assessment of Influenza Vaccine Effectiveness in the Department of Defense (PAIVED) study is a multicenter trial assessing influenza vaccine effectiveness with annual enrollment over 4 consecutive influenza seasons (2018/2019-2021/2022). Data from PAIVED provides an opportunity to evaluate influenza-like illness (ILI) in healthcare workers (HCWs) compared to non-HCWs.

METHODS: Participants in the PAIVED study were recruited from September to January in each influenza season and received egg-based, cell-based, or recombinant influenza vaccine. If a participant reported an ILI, they submitted a nasal swab for pathogen detection and a symptom diary for 7 days. For this analysis, vaccine groups were pooled and multivariable regression models were performed.

RESULTS: Among the 13 959 participants included in this analysis, 35% were HCWs. Healthcare workers were more likely to be female, white, and 25-44 years of age. In addition, HCWs were more likely to report ILIs than non-HCWs (24.1% vs 17.4%, P < .01), and this difference persisted in our multivariable model (RR 1.16 [95% CI 1.08, 1.24]). No statistically significant differences were observed between HCWs and non-HCWs in specific pathogen detection. In terms of ILI severity, HCWs reported 0.28 more days of missed work (95% CI 0.01, 0.55), 0.36 fewer days with fever (-0.60, -0.13), and, in general, reported less severe ILI symptoms in the FLU-PRO diaries.

CONCLUSIONS: Healthcare workers enrolled in PAIVED reported more ILIs during the study period than non-HCWs, despite all participants receiving influenza vaccination. Further work is needed to reduce the risk of ILIs in HCWs.

CLINICAL TRIALS REGISTRATION: A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED): NCT03734237, Study Details | A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD | ClinicalTrials.gov.

Original language	English
Pages (from-to)	ofaf728
Journal	Open Forum Infectious Diseases
Volume	13
Issue number	1
DOIs	https://doi.org/10.1093/ofid/ofaf728
State	Published - Jan 2026

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10.1093/ofid/ofaf728

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Liberg, R., Schmidt, K., Schofield, C., Ganesan, A., Campbell, W., Hrncir, D., Lalani, T., Warkentien, T., Mende, K., Markelz, A. E., Berjohn, C. M., Housel, L., Modi, J. R., Saperstein, A., Williams, A., McClenathan, B., Spooner, C., Seshadri, S., Maves, R. C., ... Richard, S. A. (2026). Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers: Findings From the PAIVED Study. Open Forum Infectious Diseases, 13(1), ofaf728. https://doi.org/10.1093/ofid/ofaf728

@article{964f724b238b440aa73dbb2a84301168,

title = "Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers: Findings From the PAIVED Study",

abstract = "BACKGROUND: The Pragmatic Assessment of Influenza Vaccine Effectiveness in the Department of Defense (PAIVED) study is a multicenter trial assessing influenza vaccine effectiveness with annual enrollment over 4 consecutive influenza seasons (2018/2019-2021/2022). Data from PAIVED provides an opportunity to evaluate influenza-like illness (ILI) in healthcare workers (HCWs) compared to non-HCWs.METHODS: Participants in the PAIVED study were recruited from September to January in each influenza season and received egg-based, cell-based, or recombinant influenza vaccine. If a participant reported an ILI, they submitted a nasal swab for pathogen detection and a symptom diary for 7 days. For this analysis, vaccine groups were pooled and multivariable regression models were performed.RESULTS: Among the 13 959 participants included in this analysis, 35% were HCWs. Healthcare workers were more likely to be female, white, and 25-44 years of age. In addition, HCWs were more likely to report ILIs than non-HCWs (24.1% vs 17.4%, P < .01), and this difference persisted in our multivariable model (RR 1.16 [95% CI 1.08, 1.24]). No statistically significant differences were observed between HCWs and non-HCWs in specific pathogen detection. In terms of ILI severity, HCWs reported 0.28 more days of missed work (95% CI 0.01, 0.55), 0.36 fewer days with fever (-0.60, -0.13), and, in general, reported less severe ILI symptoms in the FLU-PRO diaries. CONCLUSIONS: Healthcare workers enrolled in PAIVED reported more ILIs during the study period than non-HCWs, despite all participants receiving influenza vaccination. Further work is needed to reduce the risk of ILIs in HCWs.CLINICAL TRIALS REGISTRATION: A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED): NCT03734237, Study Details | A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD | ClinicalTrials.gov.",

author = "Ryan Liberg and Kat Schmidt and Christina Schofield and Anuradha Ganesan and Wesley Campbell and David Hrncir and Tahaniyat Lalani and Tyler Warkentien and Katrin Mende and Markelz, {Ana E} and Berjohn, {Catherine M} and Laurie Housel and Modi, {Jitendrakumar R} and Adam Saperstein and Alan Williams and Bruce McClenathan and Christina Spooner and Srihari Seshadri and Maves, {Ryan C} and Powers, {John H} and O'Connell, {Robert J} and Simons, {Mark P} and Pollett, {Simon D} and Coles, {Christian L} and Colombo, {Rhonda E} and Timothy Burgess and Richard, {Stephanie A}",

note = "Published by Oxford University Press on behalf of Infectious Diseases Society of America 2026.",

year = "2026",

month = jan,

doi = "10.1093/ofid/ofaf728",

language = "English",

volume = "13",

pages = "ofaf728",

journal = "Open Forum Infectious Diseases",

issn = "2328-8957",

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Liberg, R, Schmidt, K, Schofield, C , Ganesan, A, Campbell, W, Hrncir, D, Lalani, T, Warkentien, T, Mende, K, Markelz, AE, Berjohn, CM, Housel, L, Modi, JR, Saperstein, A , Williams, A, McClenathan, B, Spooner, C, Seshadri, S, Maves, RC, Powers, JH, O'Connell, RJ, Simons, MP, Pollett, SD, Coles, CL , Colombo, RE, Burgess, T & Richard, SA 2026, 'Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers: Findings From the PAIVED Study', Open Forum Infectious Diseases, vol. 13, no. 1, pp. ofaf728. https://doi.org/10.1093/ofid/ofaf728

TY - JOUR

T1 - Healthcare Workers Have More Frequent and Less Severe Influenza-Like Illness Than Non-healthcare Workers

T2 - Findings From the PAIVED Study

AU - Liberg, Ryan

AU - Schmidt, Kat

AU - Schofield, Christina

AU - Ganesan, Anuradha

AU - Campbell, Wesley

AU - Hrncir, David

AU - Lalani, Tahaniyat

AU - Warkentien, Tyler

AU - Mende, Katrin

AU - Markelz, Ana E

AU - Berjohn, Catherine M

AU - Housel, Laurie

AU - Modi, Jitendrakumar R

AU - Saperstein, Adam

AU - Williams, Alan

AU - McClenathan, Bruce

AU - Spooner, Christina

AU - Seshadri, Srihari

AU - Maves, Ryan C

AU - Powers, John H

AU - O'Connell, Robert J

AU - Simons, Mark P

AU - Pollett, Simon D

AU - Coles, Christian L

AU - Colombo, Rhonda E

AU - Burgess, Timothy

AU - Richard, Stephanie A

N1 - Published by Oxford University Press on behalf of Infectious Diseases Society of America 2026.

PY - 2026/1

Y1 - 2026/1

N2 - BACKGROUND: The Pragmatic Assessment of Influenza Vaccine Effectiveness in the Department of Defense (PAIVED) study is a multicenter trial assessing influenza vaccine effectiveness with annual enrollment over 4 consecutive influenza seasons (2018/2019-2021/2022). Data from PAIVED provides an opportunity to evaluate influenza-like illness (ILI) in healthcare workers (HCWs) compared to non-HCWs.METHODS: Participants in the PAIVED study were recruited from September to January in each influenza season and received egg-based, cell-based, or recombinant influenza vaccine. If a participant reported an ILI, they submitted a nasal swab for pathogen detection and a symptom diary for 7 days. For this analysis, vaccine groups were pooled and multivariable regression models were performed.RESULTS: Among the 13 959 participants included in this analysis, 35% were HCWs. Healthcare workers were more likely to be female, white, and 25-44 years of age. In addition, HCWs were more likely to report ILIs than non-HCWs (24.1% vs 17.4%, P < .01), and this difference persisted in our multivariable model (RR 1.16 [95% CI 1.08, 1.24]). No statistically significant differences were observed between HCWs and non-HCWs in specific pathogen detection. In terms of ILI severity, HCWs reported 0.28 more days of missed work (95% CI 0.01, 0.55), 0.36 fewer days with fever (-0.60, -0.13), and, in general, reported less severe ILI symptoms in the FLU-PRO diaries. CONCLUSIONS: Healthcare workers enrolled in PAIVED reported more ILIs during the study period than non-HCWs, despite all participants receiving influenza vaccination. Further work is needed to reduce the risk of ILIs in HCWs.CLINICAL TRIALS REGISTRATION: A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED): NCT03734237, Study Details | A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD | ClinicalTrials.gov.

AB - BACKGROUND: The Pragmatic Assessment of Influenza Vaccine Effectiveness in the Department of Defense (PAIVED) study is a multicenter trial assessing influenza vaccine effectiveness with annual enrollment over 4 consecutive influenza seasons (2018/2019-2021/2022). Data from PAIVED provides an opportunity to evaluate influenza-like illness (ILI) in healthcare workers (HCWs) compared to non-HCWs.METHODS: Participants in the PAIVED study were recruited from September to January in each influenza season and received egg-based, cell-based, or recombinant influenza vaccine. If a participant reported an ILI, they submitted a nasal swab for pathogen detection and a symptom diary for 7 days. For this analysis, vaccine groups were pooled and multivariable regression models were performed.RESULTS: Among the 13 959 participants included in this analysis, 35% were HCWs. Healthcare workers were more likely to be female, white, and 25-44 years of age. In addition, HCWs were more likely to report ILIs than non-HCWs (24.1% vs 17.4%, P < .01), and this difference persisted in our multivariable model (RR 1.16 [95% CI 1.08, 1.24]). No statistically significant differences were observed between HCWs and non-HCWs in specific pathogen detection. In terms of ILI severity, HCWs reported 0.28 more days of missed work (95% CI 0.01, 0.55), 0.36 fewer days with fever (-0.60, -0.13), and, in general, reported less severe ILI symptoms in the FLU-PRO diaries. CONCLUSIONS: Healthcare workers enrolled in PAIVED reported more ILIs during the study period than non-HCWs, despite all participants receiving influenza vaccination. Further work is needed to reduce the risk of ILIs in HCWs.CLINICAL TRIALS REGISTRATION: A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD (PAIVED): NCT03734237, Study Details | A Pragmatic Assessment of Influenza Vaccine Effectiveness in the DoD | ClinicalTrials.gov.

U2 - 10.1093/ofid/ofaf728

DO - 10.1093/ofid/ofaf728

M3 - Article

C2 - 41531506

SN - 2328-8957

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SP - ofaf728

JO - Open Forum Infectious Diseases

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