Trump's coronavirus diagnosis reveals how testing alone doesn't work — wearing a mask and social distancing are important too

• President Trump has tested positive for the coronavirus, along with First Lady Melania Trump.
• So far, Vice President Mike Pence, and former Vice President Joe Biden have both tested negative for the virus, but it's still possible their results could change in the coming days.
• The outbreak at the White House is a reminder that testing, even when done frequently, is not a fail-safe virus-fighting strategy on its own.
• Distancing, isolating, and masking are all still vitally important.
• People can transmit the virus best to others before they ever show symptoms, which means that by the time a lot of people go in for a test, they could have already exposed others, if they haven't been distancing or wearing a mask.

President Donald Trump and First Lady Melania have both tested positive for the coronavirus, as Trump announced in a tweet early Friday.

The news came at the end of a week Trump spent zig-zagging across the country, standing about 10 feet away from former Vice President Joe Biden during the first presidential debate in Ohio on Tuesday, and subsequently campaigning in both Minnesota on Wednesday, and New Jersey on Thursday.

Trump's longtime advisor, Hope Hicks, who was with him in Minnesota, also tested positive for the virus, while former Vice President Joe Biden, Vice President Mike Pence, as well as Trump and Melania's son Barron, have all tested negative, so far.

The New York Times reported that the president had seemed a bit under the weather at recent campaign events. In Duluth, Minnesota on Wednesday, Trump spoke for 45 minutes, about half his usual speech time on the trail, and in New Jersey Thursday, "he seemed lethargic," the Times said.

"The president does have mild symptoms," White House Chief of Staff Mark Meadows confirmed to reporters outside the White House on Friday, adding that both Trump and Melania "remain in good spirits."

But White House insiders say that, testing aside, the president and his entourage have followed very few of the simple precautions that public health experts have been ceaselessly recommending to help guard against the virus's spread.

The White House has been relying on testing alone, foregoing masks and distance

The president's diagnosis is a clear indication that testing — taken on its own — is not a winning coronavirus prevention strategy.

"It was a frustrating thing to watch and happen because there are still people on the White House staff who I know very well who don't take it seriously," Olivia Troye, a former senior adviser for the White House coronavirus task force, told the Daily Beast on Friday.

"You walk into the West Wing, there are signs saying you should be wearing masks, but hardly anybody followed the protocol. And even when you did wear a mask, it felt awkward."

Troye added: "I'm actually surprised that it took this long" for the president to get infected.

As public health experts have been saying for months now, effective coronavirus prevention requires a combination approach: masks, tests, social distancing, and isolation (for infected cases) as well as quarantining (of those who might've been exposed).

It's a toolbox that, when dispatched comprehensively, has worked well to fight outbreaks around the world, in places including New Zealand, South Korea, and Singapore.

But Trump rarely wears his mask, and has continued to host many in-person meetings at the White House, mask-free.

"I put a mask on when I think I need it," he said during Tuesday's presidential debate. "Tonight, as an example, everybody's had a test and you've had social distancing and all of the things that you have to."

Test results can change

Even when it comes to testing, the president has said before that it is "not something I want to do every day."

Testing, on its own, is not a great virus-fighting strategy anyway, for a few reasons.

First of all, testing is not completely accurate (especially the rapid, 15-minute kind that is so often in use at the White House). Laboratory-confirmed tests, which take longer to produce results, are pretty good at diagnosing illnesses, but those can still be wrong too, up to as much as 30% of the time.

On Friday, former Vice President Joe Biden, whose campaign follows far stricter anti-virus protocols, said he'd tested negative for the virus, after Trump announced he was sick.

But given that the coronavirus usually incubates in the body for at least a few days, it's possible Biden's test results could still change.

The Minnesota Department of Health recommends waiting five to seven days after an event to get tested (it has not been that long since Tuesday night's debate yet). Even if that initial test comes back negative, it's still a good idea to remain cautious and "get tested again around 12 days after the event," the department said.

What's more, some infections may always go undetected, and those people can still, unknowingly, transmit their virus well to others.

Another reason testing is not a fail-safe is because, by design, it is not continuously monitoring people at every moment of the day. As the level of virus in your body fluctuates, a test may become better (or worse) at detecting its presence. Even the NFL, which is administering daily COVID-19 tests to players this season, has already had an outbreak.

"A negative test one day does not mean you're going to be negative the next day," US coronavirus testing coordinator Admiral Brett Giroir told reporters in August. "It still does not obviate your strict adherence to physical distancing, wearing a mask, avoiding crowded places — do not risk the vulnerable."

This means that it's possible more cases could be diagnosed, related to the president's infection, in the coming days.