Can influenza viruses circulate at the same time as SARS-CoV-2, the virus that causes COVID-19?

Yes. Both viruses can circulate at the same time, and a person can be infected with both viruses at the same time. Illnesses experienced by people co-infected with influenza and SARS-CoV-2 are more likely to be severe compared with those infected with only SARS-CoV-2 or influenza alone. The extent to which SARS-CoV-2 and influenza viruses will co-circulate during the upcoming 2023–24 fall and winter respiratory virus season is unknown.