Coronavirus testing needs to triple before the US can reopen, experts say

NEW YORK (NYTIMES) - As some governors consider easing social distancing restrictions, new estimates by researchers at Harvard University suggest that the United States cannot safely reopen unless it conducts more than three times the number of coronavirus tests it is currently administering over the next month.

An average of 147,000 people per day have been tested for the coronavirus nationally so far this month, according to the Covid Tracking Project, which as of Monday (April 20) reported just over four million total tests across the country.

To reopen the United States by mid-May, the number of daily tests performed between now and then should be 500,000 to 700,000, according to the Harvard estimates.

That level of testing is necessary to identify the majority of people who are infected and isolate them from people who are healthy, according to the researchers.

About 20 per cent of those tested so far were positive for the virus, a rate that the researchers say is too high.

"If you have a very high positive rate, it means that there are probably a good number of people out there who have the disease who you haven't tested," said Dr Ashish Jha, the director of the Harvard Global Health Institute.

"You want to drive the positive rate down, because the fundamental element of keeping our economy open is making sure you're identifying as many infected people as possible and isolating them."

The researchers said that expanded testing could reduce the rate to 10 per cent, which is the maximum rate recommended by the World Health Organisation. In Germany, that number is 7 per cent, and in South Korea, it is closer to 3 per cent.

There is variation in the rate of testing and positive results among states, but most need to administer more tests to get to the level the researchers suggest - a minimum of about 152 tests per 100,000 people each day.

In most states, people who had severe symptoms, worked in health facilities or were otherwise hospitalised were given priority for testing.

The goal of the testing level recommended by the researchers would be to test nearly everyone who has mild or severe flu-like symptoms, and an average of 10 contacts for each person who tests positive for the virus.

A shortage of test kits and technical flaws in the United States significantly delayed more widespread testing of the virus, letting it spread undetected for weeks.

With more than 770,000 cases as of Monday, the country has the highest number of known cases in the world.

Health experts said that if the United States had tested earlier and more, the outbreak would have been better contained.

Dr Caitlin Rivers, an assistant professor at the Johns Hopkins Centre for Health Security, said that since that did not happen and the virus spread rapidly, it has made sense to prioritise testing for those in hospitals in recent weeks.

"It does make sense, given constraints, to focus on people with severe illness, because you need that information to guide their care," Dr Rivers said.

In mid-May, however, when the researchers estimate infections will have subsided somewhat and states are looking to reopen their economies, Dr Jha believes vastly expanded testing will be crucial.

"I want to be able to identify everybody who is even mildly symptomatic," he said. "So when I wake up one morning and have a sore throat and a fever, I should be able to go get tested. And then I want to be able to test all of my contacts if I turn out to be positive, so that I can do the test, trace and isolate strategy that's so critical to allowing us to open up and stay open."

New Jersey currently has the highest positive rate among all states - about half of the 178,000 coronavirus tests that it has conducted so far have come back positive.

That suggests that many of the people in the state who have the coronavirus have not been tested. And recently, testing in New Jersey has started to decline.

The state's testing has been hindered by setbacks, including long lines at testing facilities and a shortage of health care workers and testing swabs.

Mr Christopher Neuwirth, an assistant commissioner at New Jersey's Health Department, said the state's recent lag in testing could also indicate that fewer people are trying to get tested.

"In the days and weeks up until testing was available, there was a huge pent-up demand," Mr Neuwirth said.

After that, he said, the public became more aware of the criteria for testing.

"People really paid attention and really heard the messaging that you have to be symptomatic."

That messaging will have to be reversed, Dr Jha said, once testing is expanded.

"We need to switch from saying to people, 'if you have mild symptoms, if you're not feeling super sick, don't come and stay at home,' to 'if you have any symptoms, you need to come in to get tested right away,'" he said.