How long are you contagious if you have COVID?

No one wants to give COVID-19 to a loved one (or anyone). But determining how long you’re contagious isn’t an exact science, as it can vary from person to person.

So it can be difficult to find out if you are endangering others. However, there are rules you can follow and things you can know to help protect those around you — as well as lessen other concerns about your infection.

Here, experts share guidelines for how long you could be spreading COVID-19 and when you’re most contagious, including with the viral strain currently dominant.

Most people are contagious for about 10 days.

It’s not always clear how long a person is contagious because, like many things with COVID-19, the exact timeline depends on many factors, said Dr. Stuart Ray, a professor of medicine and infectious diseases at Johns Hopkins University School of Medicine in Baltimore.

But, Ray said, the conventional wisdom is that you’re contagious and should isolate for a full five days after your symptoms begin — with your first day of symptoms counting as day zero.

But keep in mind that you are not free after five days.

“It’s often then said that you should wear a mask afterwards to protect others because it’s hard to know for sure how long you’ll be contagious,” Ray said.

“That period often lasts up to 10 days,” he added — and again, your first day of symptoms counts as day zero.

Long story short, you are likely to be contagious for about 10 days after symptoms begin. You must isolate for the first five days and wear a mask on at least days six through ten.

But at certain points you are most contagious.

The stage when you’re most contagious starts about 48 hours before you test positive and ends five days after your symptoms begin, according to Dr. Neha Vyas, a family physician at the Cleveland Clinic in Ohio. She called this the “period of maximum contagiousness.”

So at this stage you’ll want to be extra careful, although it’s hard to know if you’re sick before you get symptoms, making those first 48 hours very tricky.

Meanwhile, the amount of time between infection and symptoms has been getting shorter and shorter as COVID-19 mutates, meaning that omicron subvariants like XBB – currently the dominant strain in the US – could spread more quickly.

If you are exposed to someone who tests positive for COVID-19, you can test yourself even before you have symptoms. Or, if you recently attended a crowded indoor event, you can test a few days later. Furthermore, there’s not really a way to know you’re infected before you start showing symptoms.

And in the later period of your illness, remember that you can still spread COVID-19. That’s why it’s important to wear a mask until at least the 10-day mark.

If you have symptoms after 10 days, you can still spread the virus.

Anyone whose symptoms persist beyond day 10 and who continues to test positive probably can passing the virus on to others. If that’s you, keep wearing a mask and avoid indoor areas and events, Ray said.

“Lfu are immunocompromised or you really had one [severe] COVID infection…then you could still be contagious for 20 days” after symptoms begin, added Vyas.

Long periods of contagiousness like this are rare, she stressed. But if you fall into either of these two categories, talk to your doctor for further guidance.

If possible, isolate yourself from others in your home for five days.  After that, wearing a mask is important.
If possible, isolate yourself from others in your home for five days. After that, wearing a mask is important.

Home antigen tests are a good way to determine if you are still contagious.

It’s not uncommon for someone to test positive on a lab test after a COVID-19 infection for weeks, “but it would be very unusual for someone to test positive on an antigen test for weeks,” Ray said.

Antigen tests are the type you may have picked up at the pharmacy (from brands like iHealth) or received from the government (which, by the way, still sends out free tests).

Ray added that a positive antigen test is correlated with a virus’s ability to grow and infect. So if you have a positive antigen test, you are probably contagious.

And that also works the other way around.

“We generally say that if your symptoms are completely gone and you have a negative test, it’s unlikely you’re contagious,” Ray said.

If you want to be extra careful, you can take two COVID tests.

If you’re past the 10-day mark and no longer symptomatic, but are concerned about possibly spreading the virus to a loved one, there are things you can do.

“You can do two COVID tests 48 hours apart,” Vyas said. “If they’re both negative, that’s possible [be] pretty sure you’re not contagious anymore.”

She added that most people don’t need to do this as long as they follow the 10-day guidance. But if you’re nervous about passing on the virus, this is a good tactic.

If you live in a house with others, do what you can to protect them.

“If possible, an infectious person should use a separate bedroom and bathroom, especially during this five-day period [after symptoms begin]said dr. Ali Khan, the chief medical officer at Oak Street Health.

If that’s not possible, wear a properly fitted mask – ideally an N95 or KN95 – around other people in your home.

Khan added that an infected person should have their own crockery and sheets, and they should avoid items that are frequently touched.

“Don’t forget to wash your hands regularly,” Khan said — and this includes people who aren’t infected.

Finally, to protect yourself and your loved ones, make sure you are up to date on your COVID-19 boosters.

“It’s certainly not too late to get COVID-19 and flu shots because they will still curb severe symptoms even if you get sick,” Khan said.

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