A person with COVID-19 is generally contagious starting about 48 hours before symptoms begin (or from the date of positive test if asymptomatic) and remains contagious typically for about 7 to 10 days after symptoms start. The contagious period usually ends when symptoms have been improving for at least 24 hours (48 hours if gastrointestinal symptoms are present) and the person has had no fever without the use of fever-reducing medications for at least 24 hours. After this time, the person is generally considered no longer contagious, although some precautions may still be advised for a few more days to reduce risk to others. In some cases, like people with weakened immune systems or severe illness, contagiousness may last longer and require individualized guidance.

Key Points on Contagiousness with COVID-19

• Contagious from 2 days before symptoms or from positive test if no symptoms.
• Generally contagious for 7 to 10 days after symptoms start.
• No fever for at least 24 hours and improving symptoms usually indicate no longer contagious.
• Some may remain contagious longer, particularly immunocompromised individuals.
• CDC recommends mask use for 5 days after isolation to reduce spread even after contagious period ends.
• Testing positive by rapid antigen test usually corresponds to contagiousness; PCR tests can remain positive longer but do not reflect infectiousness.

These guidelines reflect current recommendations and research as of late 2024 and early 2025.