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More than half of U.S. states will have to significantly step up their Covid-19 testing to even consider starting to relax stay-at-home orders after May 1, according to a new analysis by Harvard researchers and STAT.

The analysis shows that as the U.S. tries to move beyond its months-long coronavirus testing debacle — faulty tests, shortages of tests, and guidelines that excluded many people who should have been tested to mitigate the outbreak — it is at risk of fumbling the next challenge: testing enough people to determine which cities and states can safely reopen and stay open. Doing so will require the ability to catch reappearances of the coronavirus before it again spreads uncontrollably.

The White House has repeatedly expressed confidence about states’ ability to do enough testing to begin a phased reopening of the economy. In a briefing last Thursday, President Trump said he disagreed with comments by Anthony Fauci, the top government infectious disease expert, that “we are not there yet” with the number of tests and the capacity to perform them. “No, I think we’re doing a great job in testing,” the president said.

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But the new state-by-state review reveals a far more fragmented picture: 31 states and the District of Columbia were doing too little testing last week to identify most infected people in a timely manner. Ten states would need to increase their daily testing totals by at least 10,000 to do so by May 1. New York, for instance, would have to perform more than 100,000 more tests a day, and New Jersey 68,000 more. Nineteen states — all but two in the South or the western half of the country — are already doing enough testing.

Testing targets by state

Hover over each state to see the number of Covid-19 tests it would have to perform each day to be prepared to reopen after May 1. Alissa Ambrose/STAT Data source: Harvard Global Health Institute

Most assessments of the amount of testing that will be needed over the next few months are national. But while those are a good starting point, they do not give individual states, let alone cities, much guidance. “You can’t just take the national number and scale it to states by their population,” said Ashish Jha, director of the Harvard Global Health Institute. “You have to base it on the size of the outbreak in a state.”

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At STAT’s request, Jha and his colleagues at the institute calculated the number of tests that each state would need to be doing as of May 1. STAT then compared those numbers to each state’s daily testing totals in an average week in mid-April, using data collected by the Covid Tracking Project.

The results show that states with few Covid-19 cases and deaths so far will need to perform relatively few tests: between 68 and 145 per day in Alaska and between 31 and 156 in Montana, for instance. States harder hit by the pandemic face a much heavier lift: New York would have to do 130,000 to 155,000 tests every day, New Jersey 75,000 to 90,000, and both Massachusetts and Illinois about 30,000 to 35,000.

Many hard-hit states are not even close to their goals. New York, for instance, has been averaging barely more than 20,000 tests per day since mid-April. New Jersey has been doing about 7,000, on average. Neither has announced reopening plans or dates, giving them time to ramp up testing. Massachusetts and Illinois are in no better shape, conducting just under 7,000 a day. Michigan, Connecticut, and Colorado are all about 15,000 tests a day below their May 1 targets. Texas, with more than 9,000 tests a day, and Washington state, with more than 3,000, are already doing enough.

Testing gaps by state

Hover over each state to see the difference between the average number of daily tests it was performing the week ending April 22 and its May 1 daily testing target. Alissa Ambrose/STAT Data source: Harvard Global Health Institute, Covid Tracking Project, STAT

The more worrisome gap involves states that, despite having thousands of Covid-19 cases, are easing mitigation strategies by, for instance, allowing more businesses and public spaces such as beaches to reopen. To catch hot spots before they turn into wildfires of disease, Georgia must do 9,600 to 10,000 tests per day; it has been averaging around 4,000. Florida will need 16,000; in the last week it has been hitting just above 10,000. South Carolina is a rare bright spot: It will need 1,200 to 1,600 tests per day and has been averaging close to the low end of that, with at least 1,500 tests on several recent days.

In the last week, the U.S. as a whole conducted 1.6 million tests, according to the Covid Tracking Project. The Harvard team says twice that many tests will be needed — at minimum.

Performing enough tests is only one of the essential steps before states can reopen, experts say. Test results also have to be returned more quickly, public health workers must identify and contact potentially exposed people, and hospitals and nursing homes require adequate amounts of personal protective equipment and other supplies in case a new wave of seriously ill patients crashes over them.

The Harvard institute based its calculations on best-case scenarios. If the goal were not to miss a single new infection, “you would need more than 300 million tests a day,” said Jha — testing nearly every resident of every state every day (or every few days). “That’s an interesting theoretical exercise but since it’s not going to happen, it’s policy-irrelevant. If you say that, people stop listening.”

Instead, he said, “we tried to come up with numbers that wouldn’t make governors gag.”

Jha and the institute’s Ben Jacobson crunched the numbers two ways for each state. Both start with the number of deaths projected for May 15 by Los Alamos National Laboratory, whose Covid-19 model the Centers for Disease Control and Prevention consults. Los Alamos projects that, nationally, the death toll on that day will be 545 — but more if states keep easing up on social distancing. For comparison, on April 25, the U.S. reported just over 2,065 new Covid-19 deaths.

The researchers then assume that deaths on May 15 will reflect the number of cases on May 1, since two weeks is the average time between infection and death. If 1 out of every 100 people diagnosed with Covid-19 dies (for a “case fatality rate” of 1%), then on May 1 there would be 100 times as many new cases as there would be deaths on May 15; call it 54,500 (545 times 100) cases on May 1 for the country as a whole. The case fatality rate for Covid-19 remains unknown, so if it is lower, perhaps 0.5%, then the number of cases would be greater: 109,000. Jha’s choice of 1% reflects his decision to make recommendations that are within reach of realistic testing capacity, and 1% is the rough consensus of experts now.

To control the epidemic, public health workers would need to identify those 54,500 new cases on or around May 1 in order to trace and test their contacts, quarantining those who also test positive. (The “around” is because cases don’t have to be identified right away; probably within two or three days of infection is OK.) The chances of picking precisely the right 54,500 people to test are nil.

It’s therefore necessary to test many times more than 54,500 people to find that number of cases. How many more?

Jacobson and Jha calculated that using two different methods, which serve as a check on each other.

One method is based on the fact that people most likely to be infected with the new coronavirus are also the most likely to be tested. But because of inadequate testing capacity, and because many people don’t even show symptoms, tens of thousands of cases have been missed.

Roughly 20% of U.S. tests are positive for the virus. Epidemiologists estimate that for infectious diseases such as influenza and tuberculosis, if more than 3% of people test positive, then the net is not being cast wide enough. South Korea has a 3% positive rate for its coronavirus testing. To achieve that, the U.S. would have to increase its number of daily tests to 2 million by May 1. (It should be 5 million now, but that ship has sailed.) Even 2 million seems beyond reach.

But the World Health Organization says a positive rate below 10% “reflects adequate testing,” Jha said. Using that rate, the U.S. would have to be testing 545,000 people per day by May 1 and every day thereafter, until projected deaths two weeks ahead fall.

At STAT’s request, Jacobson and Jha then applied the 10% positive rate to each state individually. That yielded an enormous range, from 155,000 a day in New York to just 18 a day in Wyoming. Is it feasible? That will vary by state, but last week California said it aims to conduct 25,000 tests a day by the end of April, up from an average of about 14,000 in recent days. The Harvard team calculated the Golden State needs about 26,000, suggesting that if California hits its goal it could well be on track to safely reopen.

As a check on their work, the researchers did the calculation a second way.

They again started with Los Alamos’ 545 projected deaths on May 15 and inferred that there were 100 times as many new cases, 54,500, on May 1. That’s a starting point for tracing contacts, which offers the best shot at containing both the current outbreak and any that threaten to erupt after shutdown orders are lifted: “Reopened” cities and states must catch and quarantine cases, then identify and test their contacts before they infect more people.

Without social distancing, each case has an estimated 19 close contacts, Jha said. With social distancing, each might have 10, again suggesting roughly half a million tests per day.

A lot of assumptions — case fatality rate, test positivity rate, and more — went into these calculations. But other researchers have come up with approximately the same number via different reasoning.

Last week, an analysis by the Rockefeller Foundation concluded that the U.S. should test 3 million people a week. Vital Strategies, the nonprofit headed by former CDC Director Tom Frieden, recommended a minimum of 450,000 tests per day. Researchers arrived at that figure by counting the number of people who have the highest priority for testing: people who are sick and their contacts, of course, but also nursing home and shelter residents, prison inmates, and vital workers in health care and public transit and other infrastructure, said epidemiologist Cyrus Shahpar of Vital Strategies.

As in the Harvard calculation, the national testing goal of 450,000 would not be evenly distributed according to state (or city) population, he said.

The White House has said that individual states and cities need to do roughly 30 tests per 1,000 people per month, as Deborah Birx, the White House’s Covid-19 response coordinator, explained at a recent briefing, citing New Orleans’ 27 tests per 1,000. Birx said that all but three states — Oregon, Maine, and Montana — had the ability to do that many tests and that the administration is working with states to ensure all the potential for testing is “brought to bear.”

Both Shahpar’s and Jha’s calculations, however, say the number of needed tests is closer to 45 per 1,000 people per month, but with significant regional variation.

And that, both say, is the lower bound of what is needed.

  • Did you look at West Virginia when you were analyzing for this article? It would have been worth a mention that we have never been about 4.5% positive and are currently at 3%. But WV frequently gets ignored in national media.

  • I didn’t see Med worker change glove after each test , They wear the same glove
    to testing covid-19 for so many peoples . { how many glove they change a day?}

  • This is interesting, and confirms my thoughts that the US is a mess. These health experts had to lower the actual number of required tests so as not to overwhelm governors with numbers that are not doable. Scary! From the very beginning, the one constant in this fight has been the need for mass testing. I just caught a clip of Rudy Giuliani, on Fox, making fun of contact tracing. We are in for much more pain.

  • Back on Feb 6th, when the CDC first released it’s COVID-19 test kits, there *might* have been a chance to contain the outbreak, if the few hundred cases back then could have been found and contact-traced and contained (I think there is agreement that the coronavirus reached the USA before the ‘first case’ guy in Seattle, probably the first week in January or so, so how many cases total by Feb 6th? 300?)

    Those tests were faulty, and the virus took off and never looked back. We did not contain it like South Korea appears to have done. Or Japan. Or Taiwan. Or Singapore.

    NOW, they want to test and track and contain when there are about a million cases? That’s just wishful thinking. Add in the at least 30% false-negative rate for the RT-PCR tests for COVID-19, and the huge percentage of asymptomatic COVID-19 infections, and you have Mission Impossible. It would be better to quarantine hotspots like NY City for two months like China did to Wuhan. Nobody out.

  • ” Florida will need 16,000; in the last week it has been hitting just above 10,000″

    This is inaccurate. This last week Florida has average slightly over 15,000 tests per day, not barely over 10,000. As this data is very easy to find, I’m wonder how accurate the rest of the data in the article is.

    • from 4/19-4/25 i see the average in florida at 12, 367, according to covidtracking.com.

      maybe there is a different set of test numbers you’re using?

    • AJ- FL Emergency management. They keep the tally attached to the floridahealthcovid19.gov site (because FLcovid19.gov would be too short).

  • Thank you! This information is badly needed. You’ve done our country a huge service.

  • False negatives are a devil. Even with a good diagnostic test, a lot of folks with the disease would get by with the single diagnostic screen. I wonder if two-stage testing of positives might be in order?

  • Businesses that do reopen still must try to maintain social distancing and take steps to keep their staff and customers safe. But that is not always possible in businesses with such close contact. We must wear a masks and gloves, but the problem is that we can’t find it where to get them.

  • Businesses that do reopen still must try to maintain social distancing and take steps to keep their staff and customers safe. But that is not always possible in businesses with such close contact. We all must wear a masks and gloves, but the problem is that we can’t find it where to buy them.

  • The purpose of the lockdowns was to slow the infection rate so as to “flatten the curve” and not overwhelm hospitals. It was never conditioned on mass testing or the development of a vaccine, both of which are likely years away.

    • Exactly right, Rich. The curve has been flattened. It’s time to open back up and let the virus run its course. The sooner we open up the sooner we achieve herd immunity.

    • If we can do both – open up while having enough testing – that’s ideal. But it has to be on a feasible timeline. Another month, maybe. Another three months, six months – no way. Anyone who thinks that is reasonable has a trust fund or a government job.

    • Without testing and tracking new infections the curve will rise again and threaten to overwhelm hospitals again. This is not a one-and-done pandemic.

    • If we let the virus run its course we’ll be right back to where we were before flattening the curve.

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