How Long Does COVID-19 Stay In Your Body?

The length of time that COVID-19 stays in the body can vary, but most people who get COVID are no longer contagious after 10 days. Those with severe COVID may remain infectious beyond 10 days and need to take additional precautions.

However, there are people in whom COVID has been known to persist for months rather than weeks. While cases like these are rare, there is increasing evidence that the virus may persist in other tissues for longer than previously thought and possibly contribute to the development of long COVID.

This article describes what most people can expect if they get COVID-19, including how long the infection lasts. It also explores why COVID stays in the body of some people longer and what that means for you.

How Long Is COVID-19 Contagious?

As a general rule, most people with mild to moderate COVID are no longer contagious 10 days after symptoms first appear. However, it can take longer for people with severe symptoms or weakened immune systems to clear the virus and no longer be contagious.

When you get COVID, you are contagious because your body is continuously shedding infectious particles (called viral shedding). Until viral shedding fully ceases, there is a chance you can infect others. The shedding can persist whether you have symptoms or not and even after you no longer test positive for COVID.

However, as time passes, the potential for infection dramatically decreases as there are generally too few viral particles for an infection to be viable.

According to a 2022 study published in Emerging Infectious Diseases, vaccinated people with mild or asymptomatic COVID experience shedding six to nine days after being diagnosed or developing symptoms. While shedding can persist well after this time, any viruses shed after the first 10 days are considered non-viable due to their low numbers.

The same may not be true for people who remain unvaccinated against COVID-19. A 2022 study published in PLoS Pathology reported that unvaccinated people continue to experience viable shedding an average of seven and a half days compared to six days for those who were vaccinated.

While a 15% difference may seem incidental, as new variants of COVID-19 continue to emerge, the length of time people are contagious may change and the difference in shedding times between vaccinated and unvaccinated people may widen.

COVID-19: What to Do if Diagnosed

In March 2024, the Centers for Disease Control and Prevention (CDC) revised its guidance on the isolation of people with diagnosed or suspected COVID.

According to the CDC, if you test positive for COVID or have symptoms of a respiratory viral infection:

• Isolate at home until you've been fever-free for 24 hours (without taking fever-reducing medication) AND your symptoms are mild and improving.
• Take additional precautions for five days following isolation, such as wearing a well-fitting mask, keeping a distance from others, and washing your hands often.

Why Some People Have Longer COVID Infection

For some people, a COVID infection can persist far longer than what would otherwise be expected. One such case presented at the 2022 European Congress of Clinical Microbiology & Infectious Diseases described an incident in which an immunocompromised person tested positive for 505 days until the time of their death.

As uncommon as this case may seem, it was not the only example. According to the presenters from King’s College London, a similar case was identified in London in which positive COVID test results were returned for more than a year in another immunocompromised individual.

While this shouldn't suggest that being immunocompromised inherently prevents you from clearing the virus, it may lengthen the time that COVID remains in the body.

Of seven other immunocompromised people monitored by the King's College researcher, the average duration of viable viral shedding was 73 days. Each had different reasons for their weakened immune state, including organ transplantation, HIV, cancer, and medical treatments used to treat other illnesses.

While the cause of this phenomenon is unknown, it is thought that the lack of an intact immune system provides the virus the opportunity to mutate and create variants that the immune system has a hard time clearing. These variants can then be passed into the larger population where they may or may not do harm.

Similar cases were identified in Spain and China where viral shedding persisted for 189 days and 169 days, respectively.

Viral Persistence and Long COVID

There is also evidence that COVID may persist in other tissues outside of the respiratory tract even when COVID tests show no sign of the virus.

According to researchers at Stanford University who monitored 113 individuals with mild to moderate COVID, nearly half (49.2%) had evidence of viral shedding in their stool. Even after the nasal swab tests came back negative, 12.7% continued to shed the virus in their stools for the next four months. By month seven, 3.8% were still shedding the virus.

In theory, this might explain why certain people develop long COVID in which symptoms persist for more than 12 weeks even when tests show no evidence of the virus. In fact, the vast majority of COVID long haulers test negative for the virus.