How long will I be contagious for Flu A, Flu B, or RSV if I test positive?
Influenza A, Influenza B, and Respiratory syncytial virus (RSV) are very contagious. You may be able to spread these respiratory illnesses to someone else before you know you are sick, as well as when you are sick with symptoms.
According to the CDC:
- People with Flu are most contagious in the first 3-4 days after their illness begins. People infected with RSV are usually contagious for 3 to 8 days and may become contagious a day or two before they start showing signs of illness.
- Some otherwise healthy adults may be able to infect others with Flu beginning one day before symptoms develop and up to 5-7 days after becoming sick.
- Some infants, and people with weakened immune systems, can continue to spread RSV even after they stop showing symptoms, for as long as 4 weeks.