This One Thing Means You Need a COVID Test—Even If You're Vaccinated

Even though breakthrough infections are rare, experts say this is a sign you need to get checked out.

In the early days of the pandemic, getting tested for COVID-19 usually followed any encounter with someone we knew who later came down with the virus. Fortunately, the highly effective vaccines that have rolled out have made the constant need for a nasal swabbing or antibody test something of a distant memory. But even though exposure to COVID may not bear the same risk for vaccinated people, experts say there is still at least one thing that means you need to get a test.

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As health experts warn that unvaccinated people are at major risk of contracting the highly contagious Delta variant that has become the dominant strain in the U.S., concern has also risen over rare "breakthrough" infections of fully vaccinated individuals. But experts say the one warning sign that a COVID test is necessary is if you develop symptoms, regardless of whether you're vaccinated or not.

"The only time you should get tested if you're fully vaccinated is if you're symptomatic, no matter what the exposure," Amesh Adalja, MD, senior scholar at Johns Hopkins Center for Health Security, told Business Insider. This can include developing a cough, congestion, sneezing, or a loss of taste and smell after you know you've been exposed to someone who has the virus.

Adalja's advice falls in line with guidance from the Centers for Disease Control and Prevention (CDC). According to the agency's website, those who are fully vaccinated should monitor themselves for symptoms after any known exposures and "get tested and stay home and away from others" if any develop.

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If you begin to feel like you're coming down with COVID, Adalja recommends following up any initial negative test results with a PCR test that also searches for other pathogens. "You also have to remember that now that many people are socially interacting, other viruses have come back—things like rhinovirus and seasonal coronaviruses—so there are other causes of cold-like symptoms," he points out.

Other experts have pointed out that taking a needless COVID test could have unintended consequences and create an overly cautious environment. "Testing people who have been vaccinated and have no symptoms could extend this pandemic forever," Monica Gandhi, MD, an infectious-diseases specialist and professor of medicine at the University of California, San Francisco, and Marty Makary, MD, a professor at the Johns Hopkins School of Medicine and Bloomberg School of Public Health, wrote in a joint op-ed published in The Washington Post on July 21. "That's because a PCR test, which still remains the gold standard of testing (over antigen-based testing), can detect just a few virus particles—or even just one."

Gandhi and Makary cite two separate published in the medical journal The Lancet and The Journal of Infectious Diseases. Both found the small amounts of viral particles that can create a positive test result aren't large enough to make someone contagious. "Indeed, such small amounts of exposure can boost immunity in the vaccinated while causing no ill effects," they add.

But besides being symptomatic, there is still at least one case in which you may legally need to get a COVID test, even if you're vaccinated. The CDC and the federal government still require that all international travelers entering the U.S. must get tested within three days before their flight, also recommending a follow-up test three to five days after their trip.

RELATED: Scientists Just Made a Startling Discovery About Vaccinated People Who Get COVID.

Zachary Mack
Zach is a freelance writer specializing in beer, wine, food, spirits, and travel. He is based in Manhattan. Read more
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