Testing Alone Doesn’t Stop the Virus

Testing Alone Doesn’t Stop the Virus
Photo: SAUL LOEB / Contributor, Getty Images

What surprised me was not that the U.S. president contracted the coronavirus, but that it took so long. He doesn’t wear a mask; he is often surrounded by others who do not wear masks; he tells people speaking to him to take off their masks. It almost seems like he was relying solely on the frequent testing of those around him to somehow stop the virus.

Testing is important, but it can’t actually stop the spread of COVID-19 on its own. Testing just tells you who has the virus. It gives you the opportunity to fight with your eyes open.

What you need to do besides just testing

The health of the whole community — even the whole world — matters, but let’s do a little thought experiment. Let’s assume you only care about one person: yourself. You show up to work every day, where you are the boss. How do you reduce your own personal chances of getting the virus?

Let’s assume you’re already staying away from people who are known to have it. Not just 1.5 metres away — you wouldn’t want to be in the same room as them. They should stay home. Not come to work. Not attend parties.

And because not everybody who has the virus knows that they have it, you should do your best to stay away from everybody you don’t absolutely need to interact with. To reduce your risk when you’re near people with unknown status, you’d wear a mask, and ask them to wear a mask (or make them wear a mask, since you’re the boss). You’d wash your hands frequently and have your staff sanitise surfaces, just for good measure.

Testing only helps if you know what to do with the results

OK, but testing should still help, right? Sure, but only if you take the appropriate actions based on the results.

Here’s where that pedantic distinction between isolation and quarantine becomes important:

  • Isolation is for people who know they have the virus.
  • Quarantine is for people who have been exposed to the virus and might have it, but do not know yet.

So if your close coworker has tested positive, they should isolate. You, since you’ve been in contact with them, should quarantine.

This protocol was apparently not being followed at the White House. Kayleigh McEnany kept showing up to work over the past few days because her tests were coming up negative, even though she had recently been in contact with other people, like Hope Hicks, who’d tested positive.

A negative test doesn’t mean you’re uninfected

Importantly, a person can have the coronavirus and still test negative. This may be because they got a false negative result. Among the possible reasons why: maybe the swab didn’t pick up enough viral RNA, or maybe the person is in the very early stages of the infection when it’s harder to detect. The FDA notes in a fact sheet on PCR testing that, “a negative result does not rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions. A negative result does not exclude the possibility of COVID-19.”

Importantly, the test the White House was using, Abbott’s ID Now test, was created for use on people with symptoms (for example, at urgent care centres) and isn’t intended to pick up the disease among people who aren’t showing symptoms yet, STAT reports. The company states that it detects 95% of cases in people “within 7 days post symptom onset.”

People with COVID can test negative several times before eventually testing positive. That may be what happened with McEnany, for example, as she had multiple exposures to people who later tested positive. It’s why Joe Biden’s negative tests don’t guarantee that he’s virus-free. Anyone who has had contact with someone who tested positive should quarantine for 14 days, as the CDC clearly states, whether they are a friend of the U.S. president or not.

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