Self-reported influenza and influenza-like symptoms in U.S. adults age 18–64 between September 1, 2019 and April 15, 2020

• Changes in health behavior because of COVID-19 may invalidate CDC flu data. This survey 5385 U.S. adults shows far higher flu-like illnesses than expected. data supports the use collected during pandemic. The Influenza-like Illness Surveillance Network (ILINet) can indicate presence novel, widespread community pathogens. Comparing week-to-week reported influenza-like illness percentages identify time year a novel pathogen is introduced. However, changes health-seeking pandemic call to question reliability 2019?2020 ILINet as comparison prior years, potentially rendering this system less reliable surveillance tool. Corroboration trends seen lends confidence validity those trends. study compares predicted versus influenza and vaccinated surrogate measure surveillance. An online was used ask US their vaccination status, whether they were diagnosed with after vaccination, experienced an other flu. Prevalence self-reported diagnosis age 18–64 who received vaccine between September 1, 2019 April 15, 2020 (n = 3,225) 5.8 %, while or (without diagnosis) 17.9 %. Flu sample flu-vaccinated significantly predicted, consistent substantially ILI’s 2019?20 compared from 2018?19, suggesting that ILI values be appropriate for years.