Seasonal Influenza & Other Respiratory Viruses

Questions & Answers

Do other respiratory viruses circulate during the flu season?

In addition to the flu virus, several other respiratory viruses also can circulate during the flu season and can cause symptoms and illness similar to those seen with flu infection. These non-flu viruses include rhinovirus (one cause of the "common cold") and respiratory syncytial virus (RSV), which is the most common cause of severe respiratory illness in young children as well as a leading cause of death from respiratory illness in those aged 65 years and older.

Does CDC recommend influenza vaccination to reduce the likelihood of getting a respiratory tract illness that could be mistaken for SARS?

No. CDC does not recommend that influenza vaccination be considered as a way to avoid confusing influenza disease with an influenza-like illness caused by SARS.

Influenza vaccination is the primary means of preventing influenza and its severe complications, including pneumonia, hospitalization, and death. Complications from influenza infection most often occur among people 65 years of age and older, people less than 65 years of age who have certain medical conditions, and children less than 2 years old. Influenza vaccination is targeted toward these high-risk groups, all people 50 to 64 years of age (because a high proportion of them have at least one high-risk condition), health-care workers, and household contacts of high-risk persons. Children under 6 months old are the pediatric group at highest risk of influenza complications, but they are too young to get a flu vaccine. The best way to protect young children is to make sure members of their household and their caregivers are vaccinated.

Influenza viruses are only one cause of influenza-like illness (fever, body aches, headaches). Even during the fall and winter influenza season, many other infectious agents (including SARS-associated coronavirus) can cause influenza-like illness, and most influenza-like illnesses are not caused by influenza viruses (or SARS-associated coronavirus). The influenza vaccine can prevent 70-90% of influenza-like illnesses caused by influenza viruses, but does not prevent influenza-like illness caused by infectious agents other than influenza viruses.