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Re-emergence of influenza Virus Circulation during 2020 in parts of Tropical Asia: Implications for Other Countries
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  • Joshua Mott,
  • Alicia Fry,
  • Rebecca Garten,
  • David Wentworth,
  • Sonja Olsen
Joshua Mott

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Alicia Fry
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Rebecca Garten
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David Wentworth
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Sonja Olsen
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Global influenza virus circulation declined and has been below traditional seasonal levels during the COVID-19 pandemic.1-3 We reviewed WHO influenza surveillance outputs from May 1-December 31, 2020 (epidemiologic weeks 18-53) from tropical Asian countries. For each country we report influenza surveillance specimens tested, and the percentage positive for influenza, by type and subtype. We compared current data to historical data from 2015-2019 in order to place the current season in historical context. Twelve included countries tested 17,407 surveillance specimens, with 592 (3.4%) testing positive for influenza viruses. From April 27-July 26, 2020 (epidemiologic weeks 18-30), specimens tested decreased from an average of 14,102 per year in 2015-2019 to 3,969 (71.9% decrease) and influenza positivity from 22% to <1%. During weeks 31-53, specimens tested decreased from an average of 24,782 per year in 2015-2019 to 13,438 (45.8% decrease) and influenza positivity from 18% to 4%. In six countries that maintained testing of surveillance specimens for >90% of weeks, influenza circulation was unseasonably low, or absent, during weeks 18-30, 2020. However, during weeks 31-53, the percentage of surveillance specimens testing positive for influenza approached or reached positivity rates of 2015-2019 in Bangladesh and Cambodia; and increased but remained lower than historical positivity in Lao PDR and Viet Nam. The data presented here are a reminder that the low levels of influenza circulation in the northern hemisphere in summer 2020 may not necessarily persist into the upcoming influenza season, and influenza surveillance and prevention strategies should continue as planned and not be delayed.
19 Jan 2021Submitted to Influenza and other respiratory viruses
19 Jan 2021Assigned to Editor
19 Jan 2021Submission Checks Completed
19 Jan 2021Editorial Decision: Revise Minor
20 Jan 20211st Revision Received
21 Jan 2021Submission Checks Completed
21 Jan 2021Assigned to Editor
22 Jan 2021Editorial Decision: Accept