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Trump's Covid-plagued White House proves testing alone can't keep America safe

Just like a pregnancy test cannot take the place of birth control, Covid-19 tests should not be seen as substitutes for robust public health strategies to reduce community transmission.
White House press secretary Kayleigh McEnany removes a mask before a television interview at the White House on Friday.Saul Loeb / AFP - Getty Images

President Donald Trump’s White House continues to rack up positive tests, from Hope Hicks to Stephen Miller. On Tuesday, press secretary Kayleigh McEnany (and two of her aides) tested positive for SARS-CoV2, the coronavirus that causes Covid-19. Despite knowing that she was in close contact with both the president and top adviser Hope Hicks prior to their diagnoses, McEnany not only refused to quarantine, but even continued to give briefings with reporters without a mask.

Her stated reason for this behavior, up until Monday afternoon? She hadn’t tested positive yet.

This behavior highlights a fundamental and dangerous misunderstanding of the point of Covid-19 tests — and their limitations. If we don’t know how to interpret and respond to tests, we risk the kind of disaster now unfolding at 1600 Pennsylvania Ave.

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To be clear, testing is not a prevention strategy. Just like a pregnancy test cannot take the place of birth control, Covid-19 tests should not be seen as substitutes for robust strategies to reduce community transmission. It is part of the public health approach, but not for the reasons people think.

The first and most familiar reason people get tested is to obtain a definitive diagnosis. This type of testing is most often done for individuals with symptoms — people who have a cough, fever, loss of taste or smell, or fatigue. Asymptomatic contacts of a known Covid-19 positive patient may also be tested to rule out infection. This type of testing is usually done with a “PCR” test, which amplifies the virus and which is currently considered the gold standard for testing, although other more rapid forms of molecular tests can also be used. Most tests on the market were approved for this type of “diagnostic” testing, and it has the most robust metrics.

The second reason to test is to monitor the disease on a population level. Individual-level accuracy is less important here. The goal is to detect positive cases before they spread. In this type of testing, we want to test frequently and widely; this is the strategy used by universities, sports teams and workplaces. Many groups are using rapid antigen tests, which are quicker but less accurate, and which have not (for the most part) been proven particularly effective in identifying asymptomatic patients; others are using novel strategies like “wastewater testing” (e.g., testing sewage).

Testing is also used to see if someone has recovered from an infection. For this purpose, an antibody test is used to see if you have mounted an effective immune response; or a repeat PCR test is used to see if you have eliminated the virus from your body. These tests are not completely accurate, though, and should not be used as the sole marker of whether it’s safe to be around other people.

The last main reason we test is to try to identity and screen Covid-19 cases before traveling or attending an event — for example, at the White House. This type of testing should be a molecular diagnostic test, such as a PCR test, because accuracy is critical, but often, as with the White House, a rapid antigen test is used instead, because of ease. This testing strategy can easily provide a false sense of security, as we saw at a recent White House ceremony where, after testing negative, most guests declined to wear masks. We now know several people who attended that ceremony have since tested positive. Guests should not be allowed to enter unmasked because of a rapid antigen test. Full stop.

Even if a negative screening test is to be believed, it represents just one point in time. It could change in a day, or in an hour.

Equally important, even if a negative screening test is to be believed, it represents just one point in time. It could change in a day, or in an hour. This seems to be the mistake McEnany made. Because this type of testing could provide inappropriate reassurance, it must be accompanied by other simultaneous public health measures, such as masking and physical distancing.

Unfortunately, as these tests were largely approved through emergency use authorizations, we do not fully know their sensitivity (how many people who have the disease will test positive) or their specificity (how many people who do not have the disease will test negative). Nor do we know their relative accuracy in different populations, such as asymptomatic individuals or pediatric patients. Once again, this means that testing alone will likely not identify every positive individual, and therefore cannot be relied on as the sole strategy to stop infection.

So to summarize:

  • A positive test is trustworthy, if you are symptomatic.
  • A group of positive tests are trustworthy, if used to demonstrate the presence of infection in a community.
  • A negative test may not be trustworthy if you had it more than a few hours ago, or if was a rapid antigen test and you are asymptomatic.
  • Antigen tests alone are not enough to identify virus on an individual level.

To be clear: A negative test is not sufficient to either break quarantine or to ignore other preventive measures, such as masks and physical distancing.

And testing is only the first step. To be useful, we then need to use the information it provides.

Quite simply, once you have a positive test, you do not pass go. You must immediately isolate yourself from others, for a minimum of 10 days (and possibly longer, depending on who you are). You do not wait for a “confirmatory” test before isolating. To stop the spread of the virus to your friends, family, co-workers and community, you should put on a mask, go home and stay there.

If you find out that you were a close contact of someone who tested positive — if you were within 6 feet for 10 to 30 minutes, or if you shared a room, or if someone sick was actively coughing on you — you also should not pass go. You must quarantine yourself until you are out of the infectious period, regardless of any test results. Again, the point of this quarantine is to stop the chain of transmission, and to protect your friends, family, co-workers and community. There are some exceptions, for truly critical workers like doctors, etc., but even these workers must strictly adhere to wearing masks, hand-washing and social-distancing protocols.

Finally, if you have a negative test, congrats! But if it’s a negative antigen test and you’re symptomatic, you should follow it with a PCR; and if it’s a negative antigen test, you still should wear a mask, wash your hands and maintain physical distancing. Why? Because you could be presymptomatic, or be one of those 10 percent to 40 percent of people who falsely test negative on the first test.

And, of course, once a workplace outbreak — such as the spread of Covid-19 within the White House — has been identified, the workplace should collaborate with contact tracers. To quote from the Centers for Disease Control and Prevention website, “Employers can assist the health department by providing further identification of potential contacts who worked in the same area and on the same shift, hosting a site visit for health department personnel to observe the workplace in order to make workplace-operation recommendations to help prevent further spread of the virus, and facilitating communication with employees.”

Had the White House understood and followed these simple procedures, we could have potentially stopped the chain of transmission, which has now been known to infect more than a dozen staffers, lawmakers, janitorial staff, secret service agents and more.

Had the White House understood and followed these simple procedures, we could have potentially stopped the chain of transmission.

The moment that Hicks or Trump had a positive antigen or molecular test, both of them should have isolated. They may have wanted to get a second test to confirm the infection before they announced it to the world, but they should not have put anyone else at risk from that moment forward.

As soon as these first positive tests were known, all of their close contacts, from 48 hours prior to diagnosis right through the moment they went in isolation, should have been notified and put on quarantine. This means Rudy Giuliani, Chris Christie and McEnany — two of whom have already tested positive, and the third of whom is currently awaiting results — should have gone home and stayed home. (And if they absolutely could not work from home, they would have needed to be extremely vigilant about following CDC guidelines for critical workers.) Lower-level staffers, housekeeping staff and food handlers, and other essential workers who keep the White House humming must be provided with testing and allowed to isolate if necessary. Their lives, and their communities, matter, too.

America must continue to follow the other basic public health strategies that make up for lack of testing accuracy: masking, limiting interactions to small groups, staying outdoors whenever possible, and physical distancing. No one of these is, alone, sufficient to keep us safe.

Without both understanding the purpose and limitations of testing and using our full suite of public health prevention strategies, we have little hope of stopping the virus’ spread within the White House, much less within our country.