how do you tell if you are infectious from the flu
When are you contagious? If you are infected with the flu, you are most likely to pass it to someone else from 1 day before symptoms start and up to 7 days after symptoms develop. Children may be infectious for longer than 7 days after symptoms start. Symptoms usually develop 1 to 4 days after you are infected.Because symptoms may not develop for a couple of days, you may pass the flu to someone before you know you have it.hildren may be infectious for longer than 7 days after symptoms start. Symptoms usually develop 1 to 4 days after you are infected. Because symptoms may not develop for a couple of days, you may pass the flu to someone before you know you have it.