On the morning of Oct. 2, just as the US was waking up to news that the president and first lady were infected with Covid-19, the New York Times was featuring a story with the headline “Colleges Learn How to Suppress Coronavirus: Extensive Testing.” And yet, President Donald Trump had often claimed he was getting tested regularly — maybe even every day. Does the White House outbreak erode the case for keeping schools and workplaces open with extensive, rapid testing? Testing had been looking good, with new technologies promising fast, cheap tests as a tactic to prevent Covid-19 spread while allowing more of the interactions needed for commerce, travel, education and human happiness. It’s hard to know how or whether testing failed in the White House until the president agrees to disclose who got tested, when they were tested, what kinds of tests were used, and how long it took to return results. Beyond that, testing was never geared to work in the absence of any other measures. Footage of a Rose Garden event six days earlier showed people hugging and kissing, congregating indoors with no masks, and otherwise acting as though the pandemic were on some other planet. Later in the newsworthy day of Oct. 2, Harvard epidemiology professor Michael Mina gave a scheduled press briefing to discuss, among other things, a New England Journal of Medicine article in which he argued that the world would benefit from more and faster testing even if tests were less accurate. Questioned about the White House, Mina stressed that testing can help stop such outbreaks from growing even bigger, and in this case might prevent hundreds of additional infections from rippling beyond the infected elected officials, staffers and guests. That depends, of course, on those who test positive isolating themselves right away, and those who’ve had close contact with them quarantining until they’re known to be free of the virus. It’s not clear that happened at the White House. Colleges seem to be using their testing programs more successfully. The ones getting it right should be an example to the White House, and to other workplaces. Some of the better-endowed campuses, such as Princeton, Harvard, Cornell, Northeastern and Yale, have done extensive surveillance tests of asymptomatic students and seen few cases. At the University of Illinois at Urbana-Champaign, there was an infamous outbreak exacerbated by students who tested positive and went to parties after learning their status. But after the whole student body went into a temporary quarantine, the outbreak ended and operations resumed with students getting tested twice weekly. The university’s efforts have lately been touted as a success. College-age people are at low risk of hospitalization or death from Covid-19, but they can spread the disease to others. In a piece published Sept. 29 in the Journal of the American Medical Association, CDC director Robert Redfield pointed to statistics showing a recent increase in Covid-19 cases in communities with a high proportion of college students, even as cases were going down in surrounding areas. Testing students regularly can help protect these communities. But it matters which kinds of tests are used. In his article, Harvard’s Mina argued that the standard Covid-19 test, the nasal swab analyzed with a system called PCR, is fine for diagnosis but not suited for screening — it’s too slow and gives too many false positives when people feel no symptoms. PCR picks up genetic material from the virus, but people tend to harbor small genetic fragments for weeks after their infections clear. That means PCR screening could find mostly people who were no longer contagious. Such false positives could send contact tracers on many useless trails and force quarantines on the wrong students. Worse still, people are most likely to transmit the virus in the days before and after they first get symptoms — a window that PCR tests are likely to miss in the time it takes to send samples to labs, process them and deliver results. But faster, cheaper tests exist, and by July, researchers were already proposing their use in colleges. David Paltiel, a professor in the Yale School of Public Health, recommended testing all students at least twice a week based on a model published in Journal of the American Medical Association. In an interview, he agreed with Mina that using more tests that are cheap and fast would be better than using fewer tests that are slow and expensive. He said it was shameful that the CDC is not recommending this kind of universal frequent testing for college campuses. Instead, he says, the CDC lists various examples of testing strategies but gives no advice on which to use. Perhaps that lack of leadership is one reason that some colleges aren’t doing a very good job. A story in the Texas Tribune described colleges in the state as having a haphazard strategy, offering tests with no guidance on who should be tested or why. Few students were getting tested, even when they were offered prizes. Resources can also be a limitation. At the University of Rhode Island, testing everyone all the time isnt affordable, but the school is monitoring infection rates by testing random samples of staff and students, says Gary Liguori, dean of the College of Health Sciences. And its using other measures such as deploying an app to help students locate unused space for socially distant study. The university would be testing everyone if it had the resources, says Liguori. But the school planned all summer for the return of students and is keeping infections low enough to continue holding classes. “I think the schools that have done things well are ones that made choices early and stuck to those commitments,” he said. With vastly greater resources, the White House could take a lesson from them. The president’s aides should be working with the CDC and local health authorities to dissect the outbreak — mapping out where it came from, how it spread, and where it might be going. That would not only prevent more cases, but also give valuable scientific information on how the disease is spreading. That could benefit everyone. Bloomberg