Has been said many times before 2020 https://www.clinicaladvisor.com/home/web-exclusives/most-flu-cases-asymptomatic/ https://www.contagionlive.com/view/asymptomatic-influenza-infection-rates-deserve-more-attention https://www.jwatch.org/fw108600/2014/03/17/most-flu-asymptomatic