The heightened focus produced results. From the second week of March to the first week of April, the number of Americans tested daily increased roughly 45-fold. Month over month, the comparison was even more staggering: 80 people were tested for the coronavirus on March 1, according to CDC data. More than 100,000 people were tested on April 1.
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Then, in mid-April, progress stopped. “We went up to about 150,000 tests a day, and then we plateaued there for a few weeks,” Jha, the Harvard professor, said. Only in the past two weeks or so has the country resumed increasing its capacity. States reported more than 300,000 new test results both today and yesterday, but it is unclear if that trend will be sustained into the next week.
What caused the plateau? Nobody is certain. “Some places had reagents, but not enough swabs. Some places had swabs but not the medium you transport them in … And some places had enough capacity, but they hadn’t changed their policies from when only the sickest people could get tested,” Jha said. This week, governors have continued to say they lack enough tests. In the District of Columbia, where the number of new cases is increasing, Mayor Muriel Bowser said at a press conference today that the city only had enough reagents to test about 1,500 people a day.
How many tests might eventually be enough isn’t clear, in part because the number depends on the size of the underlying outbreak. “If you have a very large outbreak, you need a lot of tests,” Jha said.
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There is a wide range in expert forecasts. Rivers told Congress this week that scaling up to 3 million to 4 million tests a week—equal to about 500,000 a day—would allow more serious contact tracing to begin. Paul Romer, a Nobel Prize–winning economist at NYU, has suggested that as many as 20 million tests might be needed every day. (He also proposes cyclically retesting every American every few weeks or so, a more aggressive approach than others have proposed.)
The Harvard Global Health Institute estimates that the U.S. needs about 1 million tests per day to isolate its current outbreak. It’s unlikely the U.S. can test that many people every day if it continues to use only the polymerase chain reaction, or PCR, nasal-swab tests currently in use, Jha said. Eventually, it will probably need one or more technological breakthroughs that allow it to test many more people more quickly and cheaply, he said. Antigen tests, which are similar to the rapid flu tests used in doctors’ offices, might be some of the first to become available.
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This lack of any plan does not only seem to mar the federal testing effort. “I can’t emphasize enough how much there is no plan for how to manage this response, let alone the recovery,” Samantha Montano, an emergency-management professor at the University of Nebraska at Omaha, told me.