The impact of the COVID-19 preventive measures on influenza transmission: molecular and epidemiological evidence

Leon King Tran; Dai-Wei Huang; Nien-Kung Li; Lucy M Li; Julia A Palacios; Hsiao-Han Chang

doi:10.1016/j.ijid.2021.12.323

The impact of the COVID-19 preventive measures on influenza transmission: molecular and epidemiological evidence

Int J Infect Dis. 2022 Mar:116:11-13. doi: 10.1016/j.ijid.2021.12.323. Epub 2021 Dec 10.

Authors

Leon King Tran¹, Dai-Wei Huang², Nien-Kung Li², Lucy M Li³, Julia A Palacios⁴, Hsiao-Han Chang⁵

Affiliations

¹ Department of Statistics, Stanford University, CA, USA.
² College of Life Science, National Tsing Hua University, Hsinchu, Taiwan.
³ Chan Zuckerberg Biohub, San Francisco, CA, USA; The Public Health Company, Goleta, CA, USA. Electronic address: lucymqli@gmail.com.
⁴ Department of Statistics, Stanford University, CA, USA; Department of Biomedical Data Sciences, Stanford School of Medicine, CA, USA. Electronic address: juliapr@stanford.edu.
⁵ Department of Life Science & Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsinchu, Taiwan. Electronic address: hhchang@life.nthu.edu.tw.

Abstract

Objective: We quantify the impact of COVID-19-related control measures on the spread of human influenza virus H1N1 and H3N2.

Methods: We analyzed case numbers to estimate the end of the 2019-2020 influenza season and compared it with the median of the previous 9 seasons. In addition, we used influenza molecular data to compare within-region and between-region genetic diversity and effective population size from 2019 to 2020. Finally, we analyzed personal behavior and policy stringency data for each region.

Results: The 2019-2020 influenza season ended earlier than the median of the previous 9 seasons in all regions. For H1N1 and H3N2, there was an increase in between-region genetic diversity in most pairs of regions between 2019 and 2020. There was a decrease in within-region genetic diversity for 12 of 14 regions for H1N1 and 9 of 12 regions for H3N2. There was a decrease in effective population size for 10 of 13 regions for H1N1 and 3 of 7 regions for H3N2.

Conclusions: We found consistent evidence of a decrease in influenza incidence after the introduction of preventive measures due to COVID-19 emergence.

Keywords: COVID-19; case; effective population size; epidemiology; genetic diversity; influenza.

MeSH terms

COVID-19* / epidemiology
COVID-19* / prevention & control
Humans
Influenza A Virus, H1N1 Subtype* / genetics
Influenza A Virus, H3N2 Subtype / genetics
Influenza, Human* / epidemiology
Influenza, Human* / prevention & control
SARS-CoV-2 / genetics
Seasons