This study clearly depicts that Influenza is a respiratory virus that causes substantial annual morbidity and mortality, including an estimated 200 000 hospitalizations and 30 000 deaths in the United States each year.1 Vaccines are available for prevention of influenza virus infections, but recent estimates have shown only moderate vaccine effectiveness (VE).2, 3 Annual variation is common, in terms of the frequency and severity of infection as well as in VE. As a result, further studies of influenza VE and transmission are needed with the goal of improving control.

Prospective, longitudinal community-based studies have a broad range of applications in respiratory virus epidemiology. These studies will be essential to better understand the extent of the pandemic caused by the novel coronavirus SARS-CoV-2 and the full range of COVID-19 illness. These studies also present unique opportunities to explore more in-depth questions about immune correlates of influenza vaccine failure as well as susceptibility to and transmission of infection. Nevertheless, they are much more resource-intensive than comparably sized studies using case-control designs.4 Ensuring adequate and timely specimen collection across a large cohort is particularly important as the circulation of respiratory viruses varies greatly on both a seasonal and annual basis.

Reference link-