Live Updates: Trump Tests Positive For Coronavirus : NPR

Regular coronavirus testing can be a valuable tool in preventing the spread of infection but only if accompanied with other critical health measures including quarantining of contacts of known positive cases, experts say.

Spencer Platt/Getty Images

hide caption

toggle caption

Spencer Platt/Getty Images

Regular coronavirus testing can be a valuable tool in preventing the spread of infection but only if accompanied with other critical health measures including quarantining of contacts of known positive cases, experts say.

Spencer Platt/Getty Images

The spread of the coronavirus inside the White House is a stark reminder of the danger of relying on testing to prevent outbreaks, experts say.

“I think the takeaway is clear: Testing alone is not a sufficient strategy to prevent spread of the virus,” says Daniel Green, an assistant professor of pathology and cell biology at Columbia University.

“A negative test does not give free license to forego all other safety measures,” Green says.

The White House has stressed President Trump and others in the presidential mansion underwent regular screening to protect against the virus. But other recommended measures to prevent transmission were shunned, such as mask wearing and staying at least six feet away from other people.

“The COVID-19 outbreak at the White House is an unfortunate demonstration that routine testing is not a substitute for wearing masks and maintaining physical distance,” says Jennifer Nuzzo, a senior scholar at the Johns Hopkins Bloomberg School of Public Health Center for Health Security.

“No test is 100% accurate and for this reason someone who tests negative is not guaranteed to be free of infection. That means, even when people are regularly tested, it important to use multiple approaches to reduce the likelihood of transmission,” Nuzzo says. “Maintaining distance from others, wearing a mask and choosing to stay in well-ventilated spaces are all important safety measures that must also be used.”

Other experts agree, noting that it’s crucial that people who are exposed to known positive case immediately quarantine for 14 days.

“As we’ve been saying throughout the response, relying on a test-only strategy to fight this pandemic will not be successful. The White House was using a test-only strategy,” says Kelly Wroblewski, director of infectious diseases at the Association of Public Health Laboratories.

“To be effectively fight COVID-19, it is essential to combine frequent testing with mask wearing, social distancing, frequent hand washing and quarantining when you have a positive test or close contact with a person who has tested positive,” Wroblewski says. “Testing alone is not enough.”

The rapid test used at the White House is especially prone to producing unreliable results.

“We know that false negatives do occur, especially early in the course of infection. Rapid tests, such as those used by the White House, are even more likely to produce false negative results, as they are less sensitive than laboratory-based PCR tests,” Green says.

This lesson will become increasingly important as testing becomes more widely available and other workplaces, schools and other places start to use testing to try to protect people. A new generation of coronavirus tests that are less expensive and produce results more quickly appear to be less reliably than the more sophisticated genetic PCR tests that have mostly been used so far.

Others say research is urgently needed to determine the best way to use testing.

“It is also very disturbing that even now, all these months into the pandemic, and with a possible second wave looming, that we do not have a better evidence base to guide public health policy,” says Steven Woloshin, a physician and researcher at the Dartmouth Institute who has studied the reliability of coronavirus tests.

“We really need trials so we can learn our way out of this crisis,” he says. “Not just trials of vaccines and treatments, but also trials establishing the best ways to open schools and universities, restaurants and so on.”