On December 27, 2021, the Centers for Disease Control and Prevention (CDC) shortened the recommended COVID-19 isolation and quarantine periods following a positive test or exposure. This change was based on data showing that virus transmission primarily occurs early in the course of illness, i.e. 1-2 days before symptoms appear and 2-3 days after. According to the updated policy:
- Individuals who test positive should isolate for 5 days and, if asymptomatic at that time, they may leave isolation if they can continue to mask for 5 days to minimize the risk of infecting others.
- For individuals who are exposed to COVID-19 and unvaccinated or more than six months out from their second mRNA vaccine dose, the recommended quarantine period is shortened from 14 days to 5 days, followed by strict mask use for an additional 5 days. If quarantine is not possible, such individuals should wear a well-fitting mask at all times when around others for 10 days after exposure.
- For individuals who are fully vaccinated, have received a booster and do not have symptoms, they are not required to quarantine, but are recommended to wear a mask for 10 days when around others, and to get tested at day five after exposure. If symptoms occur later, they should immediately quarantine until a negative test.
It is important to note the difference between isolation and quarantine. Isolation relates to behavior after a confirmed infection. Isolation for 5 days followed by wearing a well-fitting mask will minimize the risk of spreading the virus to others. Quarantine refers to the time following exposure to the virus or close contact with someone known to have COVID-19.