1. Estimating the generation time for influenza transmission using household data in the United States.
- Author
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Chan LYH, Morris SE, Stockwell MS, Bowman NM, Asturias E, Rao S, Lutrick K, Ellingson KD, Nguyen HQ, Maldonado Y, McLaren SH, Sano E, Biddle JE, Smith-Jeffcoat SE, Biggerstaff M, Rolfes MA, Talbot HK, Grijalva CG, Borchering RK, and Mellis AM
- Abstract
The generation time, representing the interval between infections in primary and secondary cases, is essential for understanding and predicting the transmission dynamics of seasonal influenza, including the real-time effective reproduction number (Rt). However, comprehensive generation time estimates for seasonal influenza, especially post the 2009 influenza pandemic, are lacking. We estimated the generation time utilizing data from a 7-site case-ascertained household study in the United States over two influenza seasons, 2021/2022 and 2022/2023. More than 200 individuals who tested positive for influenza and their household contacts were enrolled within 7 days of the first illness in the household. All participants were prospectively followed for 10 days completing daily symptom diaries and collecting nasal swabs, which were tested for influenza via RT-PCR. We analyzed these data by modifying a previously published Bayesian data augmentation approach that imputes infection times of cases to obtain both intrinsic (assuming no susceptible depletion) and realized (observed within household) generation times. We assessed the robustness of the generation time estimate by varying the incubation period, and generated estimates of the proportion of transmission before symptomatic onset, infectious period, and latent period. We estimated a mean intrinsic generation time of 3.2 (95% credible interval, CrI: 2.9-3.6) days, with a realized household generation time of 2.8 (95% CrI: 2.7-3.0) days. The generation time exhibited limited sensitivity to incubation period variation. Estimates of the proportion of transmission that occurred before symptom onset, the infectious period, and the latent period were sensitive to variation in incubation periods. Our study contributes to the ongoing efforts to refine estimates of the generation time for influenza. Our estimates, derived from recent data following the COVID-19 pandemic, are consistent with previous pre-pandemic estimates, and will be incorporated into real-time Rt estimation efforts., Competing Interests: Declaration of interest • M. S. S. reports a leadership role as Associate Director of the American Academy of Pediatrics’ Pediatric Research in Office Settings (PROS), paid to Trustees of Columbia University. All other authors report no potential conflicts. • N. M.B. reports grant/contracts from NIH to the University of North Carolina School of Medicine, Doris Duke Charitable Foundation, and North Carolina Collaboratory; participation on a DSMB or advisory board for the Snowball Study Technical Interchange; a leadership or fiduciary role on the American Society of Tropical Medicine and Hygiene Scientific Committee; and other financial or nonfinancial interests with the COVID-19 Equity Evidence Academy (RADx-UP CDCC) Steering Committee and North Carolina Occupational Safety and Health Education Research Center. • E. A. reports serving as a former consultant for Hillevax and Moderna, presenting a Merck-supported lecture at the Latin American Vaccine Summit, and receipt of grant/research support from Pfizer for pneumococcal pneumonia studies. • S. R. reports grant support from BioFire. • H. Q. N. reports grant/research support from CSL Seqirus, GSK, and ModernaTX, and honorarium for participating in a consultancy group for ModernaTX outside the submitted work. • S. H. M. reports grants/contracts from NIH, the American Academy of Pediatrics, and the Doris Duke Charitable Foundation. • E. S. reports grants or contracts to institution from Vanderbilt University Medical Center (originating at CDC #75D30121C11656). • H. K. T. has received research funding from the CDC. • C. G. G. reports participation on an advisory board for Merck, and receipt of grant/research support from AHRQ, CDC, US Food and Drug Administration, NIH, and Syneos Health. • All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.
- Published
- 2024
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