Testing Reduces, But Doesn’t Eliminate, Risk. (Still, Get One)

If you waited until this week to get one test, keep this in mind. Still, getting tested is better than not

BOSTON, MA — NOVEMBER 18: People weathered long lines at Urban League of Boston to get tested for Covid-19. Credit: Boston Globe / Getty Images

Lots of people are waiting in lines around the country to get tested for Covid-19. The fact that so many people are seeking tests is a good thing. Testing is a risk mitigation measure and good public health practice. There are still some very important things to keep in mind.

It’s safe to assume that a high proportion of people getting tested this week are doing so because they plan to gather with others for Thanksgiving on Thursday. Yet a negative test today does not mean that you definitely do not have Covid-19. Here’s why:

The incubation period for Covid-19 — the number of days between when you get infected and when you might see symptoms — can be as long as 14 days. Most people develop symptoms of the virus five to six days after they were exposed (and some people never develop noticeable symptoms). In rare cases people have developed symptoms at around two days after infection, and data suggests most people will have developed them by day 12. Now, keep in mind that people who get infected with the virus that causes Covid-19 can spread it two or three days before their symptoms start and people can be most contagious a couple days before they feel ill.

This is why most health organizations recommend people quarantine for 14 days, since it might take some time for the virus to replicate in your body to the point you test positive. It’s also why you can’t rely on testing alone to keep you and your loved ones Covid-19 free. Ideally you would be taking lots of precautions to ensure that the risk that you are positive is very low in addition to getting a Covid-19 test.

All of that being said, getting a Covid-19 test is better than not getting a Covid-19 test. If you plan to see other people and have not gotten tested, you should try to get one as soon as you can. If in addition to getting tested you practiced lots of other preventative measures like not seeing other people and wearing a mask, that’s better. Those same measures will be important if you are seeing people outside of your household. Wear a mask and try to stay outdoors.

From a public health standpoint, testing this week will catch many cases of Covid-19. I cannot support messaging suggesting it’s a futile strategy because it’s not. But testing this week will not catch all cases of Covid-19. People should still be encouraged to get tested and have easy access to do so.

It remains to be seen what kind of spike in cases will occur after the Thanksgiving holidays. There are many restrictions now in place, and many experts recommended against travel. However, over one million people took flights over this past weekend.

Next month brings more December holidays, and throughout the winter and rising case loads I highly recommend acquainting yourself with the most up-to-date and science-backed guides for testing, quarantining, and preventing Covid-19 infection. The two stories below are a great place to start.



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Alexandra Sifferlin

Alexandra Sifferlin


Health and science journalist. Former editor of Medium’s Covid-19 Blog and deputy editor at Elemental. TIME Magazine writer before that