COVID-19 is generally contagious starting from 1 to 3 days before symptoms appear and remains contagious for about 8 to 10 days after symptoms begin. Most people are most contagious around the time their symptoms peak, which tends to be around day 4 of illness, and contagiousness then gradually decreases
. The average contagious period is about eight days, but it can vary depending on factors such as the severity of illness and underlying health conditions. People with severe illness or weakened immune systems may be contagious for longer than 10 days, sometimes up to three weeks or more
. Current guidelines suggest that isolation can typically end after at least 24 hours without a fever (without the use of fever-reducing medicine) and when symptoms have improved. However, it is recommended to continue precautions such as wearing a mask and physical distancing for an additional five days after isolation ends to reduce the risk of spreading the virus further
. In summary:
- Contagious period: 1-3 days before symptoms to 8-10 days after symptom onset
- Peak contagiousness: Around day 4 of symptoms
- Longer contagiousness possible with severe illness or weakened immunity
- Isolation ends after 24 hours fever-free and symptom improvement, followed by 5 days of extra precautions
This reflects current expert understanding and CDC guidance on COVID-19 contagiousness
