Nobody likes to give COVID-19 to a family member (or anyone). However, establishing how long you're contagious isn't an exact science because it varies from person to person.

As a result, you may have difficulty determining whether you are endangering others. There are, however, guidelines you should observe and information you can learn to help safeguard others around you — and to alleviate other anxieties about your infection.

Experts discuss how long you may be able to spread COVID-19 and when you're most contagious, including with the virus strain that is now dominating.

The majority of persons are contagious for roughly 10 days.

According to Dr. Stuart Ray, a professor of medicine and infectious diseases at the Johns Hopkins University School of Medicine in Baltimore, it's not always apparent how long a person is contagious because, as with many things with COVID-19, the exact timetable relies on several factors.

The common opinion, according to Ray, is that you are contagious and must isolate for five full days after your symptoms begin, with the first day of symptoms considered as day zero.

However, keep in mind that you are not out of the woods after five days.

"It's commonly recommended after that that you should wear a mask to attempt to protect others since it's difficult to know how long you're contagious," Ray explained.

"That phase often lasts up to 10 days," he continued, and your first day of symptoms counts as day zero once more.

To summarize, you are certainly contagious for about 10 days after symptoms appear. You should isolate yourself for the first five days and wear a mask on days six through ten.

But you're most contagious at particular times.

According to Dr. Neha Vyas, a family medicine doctor at Cleveland Clinic in Ohio, the time when you're most contagious begins 48 hours before you test positive and ends five days after your symptoms start. She referred to this as the "time of maximum contagiousness."

You should be very cautious at this point because it's difficult to tell if you're sick before you have symptoms, making the first 48 hours extremely difficult.

Meanwhile, when COVID-19 mutates, the interval between infection and symptoms gets shorter and shorter, allowing omicron subvariants like XBB—currently the dominant strain in the United States—to spread more quickly.

If you've been exposed to someone who has COVID-19, you can test yourself even if you don't have symptoms. You can also take a test a few days later if you recently attended a packed indoor event. Aside from that, there's no way to tell if you're infected before you start showing symptoms.

Remember that you can still transfer COVID-19 in the later stages of your sickness, which is why you should wear a mask until at least the 10-day mark.

If you develop symptoms after 10 days, you may still be able to transfer the infection.

Anyone who has symptoms beyond day 10 and tests positive for the virus is likely to spread it to others. If that's the case, Ray advises wearing a mask and avoiding indoor locations and gatherings.

"If you are immunocompromised or have a particularly [severe] COVID infection... you could be contagious for 20 days" after symptoms appear, according to Vyas.

Long durations of contagiousness like this are uncommon, she emphasized. However, if you fall into either of those two groups, consult your doctor for more advice.

Home antigen tests can tell you if you're still contagious.

It's not uncommon for someone to test positive on a lab test for weeks after contracting COVID-19, but "it would be quite unusual for someone to test positive on an antigen test for weeks," Ray says.

Antigen tests are the type you may have purchased from a pharmacy (such as iHealth) or gotten from the government (which is still sending out free tests, by the way).

Ray went on to say that a positive antigen test is tied to a virus's potential to multiply and infect. If you have a positive antigen test, you are almost certainly contagious.

And it also works the opposite way around.

"We normally suggest that if your symptoms have resolved entirely and you have a negative test, you're unlikely to be infectious," Ray added.

You can do two COVID tests if you want to be extra careful.

There are things you can do if you've passed the 10-day mark and no longer sick, but you're worried about potentially transferring the infection to a loved one.

"You can do two COVID tests 48 hours apart," Vyas explained. "If they're both negative, you can be reasonably assured that you're no longer contagious."

She stated that most people will not need to do this if they follow the 10-day plan. However, if you're concerned about spreading the virus, this is an excellent strategy.

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If you share a house with people, you should do everything in your power to keep them safe.

"A contagious individual should utilize a separate bedroom and bathroom if possible, especially during this five-day period [after symptoms begin]," said Dr. Ali Khan, chief medical officer of Oak Street Health.

When that isn't an option, wear a well-fitting mask — preferably a N95 or KN95 — among other people in your home.

Khan went on to say that an infected person should have their own dinnerware and sheets and should avoid high-touch things.

"Don't forget to wash your hands frequently," Khan advised, adding that this applies to people who are not affected as well.

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

"It's definitely not too late to receive COVID-19 and flu vaccines, as they will still prevent severe symptoms even if you do get sick," Khan said.

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