In many cases, COVID-19 can be entirely asymptomatic. But even if the infection doesn't cause serious symptoms, it should still be taken seriously.
It’s clear at this point that asymptomatic COVID-19 infections can and do happen. In fact, a study published in JAMA Network Open found that, globally, more than 40% of confirmed COVID-19 cases were asymptomatic — and we know that asymptomatic cases can still contribute to the spread of the virus.
But it's also important to keep in mind that some of the characteristic symptoms of COVID-19 — a cough or sore throat — can be easily mistaken for other issues, like seasonal allergies or the common cold, Dr. Wafaa El-Sadr, professor of epidemiology and medicine at the Columbia University Mailman School of Public Health, told TODAY.
Others can be mild and barely noticeable, including minor congestion, low-grade fever, headache or fatigue, she said. So, especially during the current surge, "this is a time when we should have a low threshold for getting tested for COVID-19" if you have any symptoms that might be related to the coronavirus.
When should you get tested for COVID-19 if you have no symptoms?
The most obvious time to get tested for COVID-19 is, of course, when you have noticeable symptoms. But there are some other times in which it makes sense to get tested even if you have no symptoms at all, El-Sadr explained.
First, if you were exposed to someone who has COVID-19, you should get tested between five and seven days after the exposure whether or not you have symptoms yourself.
After an exposure, people who are not fully vaccinated should quarantine for at least five days. They should also wear a mask when around others and continue to monitor themselves for symptoms for a full 10 days, according to the Centers for Disease Control and Prevention.
If you're fully vaccinated and asymptomatic, you don't need to quarantine at this point. But you should also wear a mask around others and monitor yourself for 10 days in case you develop symptoms. (And, again, you should still get tested at least five days after your last exposure to someone with COVID-19.)
Second, you should get tested between three and five days after traveling internationally, according to CDC guidelines, regardless of your symptoms. (If you're traveling domestically, the CDC recommends fully vaccinated people get tested only if they develop symptoms while unvaccinated people should get tested three to five days after returning.)
Finally, if you have access to rapid tests, you should use them before attending gatherings with people that you don't live with, especially if you don't know everyone's vaccination or booster status, El-Sadr said.
What kind of test should you use?
You have two types of COVID-19 tests to choose from: rapid tests and polymerase chain reaction tests. Rapid tests have the advantages of convenience (you may be able to take them at home) and speed. But they're most accurate when assessing samples from people who have noticeable COVID-19 symptoms. So, while PCR tests may take longer to provide results, those results tend to be more accurate — especially for asymptomatic people.
If your only option is rapid tests, El-Sadr recommends taking two tests 24 hours apart for added certainty.
If you test positive for asymptomatic COVID-19, what should you do?
Whether or not you develop symptoms, if you test positive for COVID-19 you should:
Get in contact with your health care provider.
Stay home and isolate yourself. That means you should stay in a separate room and use a separate bathroom from other people in your household, if possible, the CDC says. You should also wear a mask if you have to be around other people, avoid sharing items (like cups and towels), avoid public transportation and generally avoid contact with other people.
Monitor yourself for symptoms. You will likely get specific instructions from your doctor's office about what to watch for, which might include things like taking your temperature every day.
Tell your close contacts that you tested positive and they may have been exposed.
How long do you need to stay isolated for asymptomatic COVID-19?
If you have symptoms of COVID-19, you can end isolation after five full days if you are fever-free for 24 hours (without the use of medications) and symptoms have subsided.
If you do not have symptoms, the CDC said on Dec. 27, you should isolate for five days and use a mask for five days after that. In early January, the agency said that people can use rapid antigen tests on day five, if available, but it is not required.
For people who don't have symptoms (and never develop them), day 0 is the day you test positive and day 1 is the day after that. If you do develop symptoms during your isolation, the first day of symptoms becomes your new day 0 and you'll have to start counting all over again.
The CDC updated its guidance for health care workers who test positive in late December: They can return to work after seven days if they test negative and don’t have symptoms.
“As the health care community prepares for an anticipated surge in patients due to omicron, CDC is updating our recommendations to reflect what we know about infection and exposure in the context of vaccination and booster doses,” CDC Director Rochelle Walensky said in a statement.
This story was updated on Jan. 10, 2022 to reflect new guidance from the CDC.