Influenza-like illness surveillance reveals spike in undetected COVID-19 cases in March

https://www.eurekalert.org/pub_releases/2020-06/aaft-iis062220.php


News Release 22-Jun-2020
American Association for the Advancement of Science


A surge in flu-like infections in the U.S. in March of 2020 suggests that the likely number of COVID-19 cases was far larger than official estimates, according to a new study of existing surveillance networks for influenza-like infections (ILIs). The findings support a scenario where more than 8.7 million new SARS-CoV-2 infections appeared in the U.S. during March, and estimate that more than 80% of these cases remained unidentified as the outbreak rapidly spread.

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In March of 2020, they observed a huge spike in ILIs exceeding normal seasonal numbers in various states - New York, for example, showed twice its previous record for ILIs in the fourth week of March. The authors also saw that the dynamics of non-influenza ILIs closely matched patterns of confirmed COVID-19 cases.

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