Four years after the emergence of SARS-CoV-2, experts know a lot about mutating strains, vaccine effectiveness, long COVID, and other common questions.

Why, despite widespread availability of safe, effective vaccines, have cases of respiratory illnesses including COVID-19, flu, and RSV spiked this winter?

In response to the COVID-19 variants circulating, the Biden Administration is once again making rapid COVID-19 tests available for free to the public.