According to the Centers for Disease Control and Prevention (CDC), people with mild to moderate COVID-19 may be contagious for 10 days from the first day they noticed symptoms. Those with severe COVID-19 may remain infectious beyond 10 days and may need to extend isolation for up to 20 days from the start of their symptoms. However, people with COVID-19 illness are most contagious for the first 5 days of their illness, which means they are most contagious 1 to 2 days before they develop symptoms and until 2 to 3 days after their symptoms start. The COVID-19 infectious period can vary, but most people are considered infectious from 48 hours before their symptoms start and can be infectious for up to 10 days. It is important to note that everyones immune response is different, and some people may spread the virus for different amounts of time. People who are severely sick with COVID-19 or are immunocompromised may need to isolate for longer than those who are mildly ill.