So, You’ve Been Exposed to Someone With COVID-19. When Should You Get Tested?

Korin Miller
·5 min read
Photo credit: Yulia Reznikov - Getty Images
Photo credit: Yulia Reznikov - Getty Images

From Prevention

If you’re aware you’ve been exposed to someone with a case of COVID-19, you probably have questions about what to do next. First, because the novel coronavirus has an incubation of two to 14 days—you’ll need to quarantine for two weeks, whether or not you feel sick in that time frame.

Then, you should consider getting tested so you can confirm whether or not you’ve picked up the virus yourself. The Centers for Disease Control and Prevention (CDC) recommends that the following people get tested for COVID-19:

  • People who have symptoms of COVID-19

  • People who have had close contact (within 6 feet for a total of 15 minutes or more over a 24-hour period) with someone with a confirmed case of COVID-19

  • People who have been asked or referred to get testing by their healthcare provider or local or state health department

However, COVID-19 tests aren’t exactly known for their accuracy—and because this is a relatively new virus that scientists are still studying, it’s difficult to predict its behavior from person-to-person. So, when should you get tested after you’ve been exposed to someone with COVID-19? We asked doctors to weigh in.

How long does it take for a person to show COVID-19 symptoms after they’ve been infected?

If you’re exposed to COVID-19, it’s unlikely that you’ll develop symptoms immediately after. Just in case you need a refresher from the CDC, the main symptoms include:

Why is the timing of a COVID-19 test so important?

If you get tested immediately after you’ve been exposed to the novel coronavirus (say, the next day), the results will likely come back negative, says infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security. That’s because you need to have a certain viral load (the amount of virus present in your body) for the test to detect.

A false negative can be dangerous, because you may go on to spread the virus without realizing it. “If you get tested and you’re positive, OK, you need to be isolated. But if you’re negative, that doesn’t mean you’re out of the woods until the incubation period (two weeks) has ended,” says Thomas Russo, M.D., professor and chief of infectious disease at the University at Buffalo in New York.

For example, one meta-analysis of seven studies published in the Annals of Internal Medicine found that the probability of a false negative test result decreases from 100% on day 1 after exposure to 64% on day four. On the day someone developed symptoms, they were, on average, 38% likely to get a false reading. This decreased to 20% three days after showing symptoms.

A study from the American College of Cardiology also found that most people develop symptoms about five days after they’re exposed and they’re often the most infectious two days before they develop symptoms and up to a day after their symptoms start.

So, when should you get tested after you have been exposed to COVID-19?

The CDC has issued no official guidance on testing after coronavirus exposure—and doctors have mixed opinions. Given that, it’s best to do what your doctor recommends, as they will be more aware of your health history and circumstances. The experts we spoke to generally agree on the following testing guidelines:

—If you have symptoms

Lewis Nelson, M.D., chair of the Department of Emergency Medicine at Rutgers New Jersey Medical School, recommends waiting to get tested until you develop symptoms, if you do at all. “While it is not optimal to wait for symptoms in some cases, it may be the most practical answer,” he says. Why? You should be quarantining for at least 14 days after you have close contact with someone who has COVID-19 anyway, per the CDC’s recommendations.

You should also contact your doctor to discuss how you are feeling and isolation requirements. “If you are feeling very sick, particularly having unexplained shortness of breath, you should go to the emergency department, as you should for any other medical emergency,” Dr. Nelson says. “Regardless of where you seek care, be very open about your exposure and risk of having COVID-19. Although we are universally cautious, the extra awareness is helpful.”

—If you don’t have symptoms the first week

Dr. Adalja recommends waiting at least four days to get tested, to see if the virus builds up in your body.

—If nearly two weeks pass symptom-free, but you want to know for sure

Dr. Russo recommends waiting much longer—until day 12—in case you have an asymptomatic case of the virus. “One could argue that if you are going to quarantine anyway, the value of testing primarily lies in the fact that, if you’re positive, contact tracing could occur,” he says.

Remember, if you know you’ve been exposed to someone with COVID-19, you should be quarantining both before you get tested and after. If you get a positive test result and don’t develop symptoms or get a negative result, you should still continue to quarantine for 14 days after you were exposed due to the incubation period.

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