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Int J Infect Dis
. 2020 Nov 26;S1201-9712(20)32491-7.
doi: 10.1016/j.ijid.2020.11.178. Online ahead of print.
An influenza A(H3N2) virus outbreak during the COVID-19 pandemic, Kingdom of Cambodia, 2020
Ly Sovann 1 , B Sar 2 , V Kab 3 , S Yann 4 , M Kinzer 2 , P Raftery 3 , R Albalak 2 , S Patel 3 , P Long Hay 3 , H Seng 1 , S Um 1 , S Chin 1 , D Chau 1 , A Khalakdina 3 , E Karlsson 4 , S J Olsen 2 , J A Mott 5
Affiliations
- PMID: 33249287
- DOI: 10.1016/j.ijid.2020.11.178
Abstract
Background: Coinciding with the COVID-19 pandemic, global influenza virus circulation decreased, possibly due to widespread community mitigation measures. Cambodia eased some COVID-19 mitigation measures in June and July 2020. On Aug 20th a cluster of respiratory illnesses among residents of a pagoda included persons that had tested positive for influenza A, and none that were positive for SARS-CoV-2.
Methods: On Aug 25, a response team deployed. Persons with influenza-like illness (ILI) were asked questions on demographics, illness, personal prevention measures, and residential arrangements. Respiratory swabs were tested for influenza and SARS-Cov-2 by RT-PCR; viruses were sequenced. Sentinel surveillance data were analyzed to assess recent trends in influenza circulation in the community.
Results: Influenza A(H3N2) viruses were identified in sentinel surveillance in Cambodia in July 2020, prior to the reported pagoda outbreak. Among the 362 pagoda residents, 73(20.2%) ILI cases were identified; 40 were tested with 33/40 (82.5%) confirmed positive for influenza A(H3N2). All 40 were negative for SARS-CoV-2. Among 73 residents with ILI, none were vaccinated against influenza, 47 (64%) clustered in 3 of 8 sleeping quarters; 20 (27%) reported often wearing a mask; 27 (36%) reported often washing hands; and 11 (15%) reported practicing social distancing. All viruses clustered within clade 3c2.A1 close to strains circulating in Australia in 2020.
Conclusions: Circulation of influenza viruses began in the community following a relaxing of national COVID-19 mitigation measures, and prior to this outbreak in a pagoda with limited social distancing. Continued surveillance and influenza vaccination remain needed to limit the impact of influenza globally.
Keywords: COVID-19; Cambodia; H3N2 subtype; disease outbreak; influenza A virus.