April 27, 2020
At a rate of 1.6 million tests per week, the US is conducting about half of the tests necessary to safely begin reopening, according to a new analysis reported by STAT News. Using mortality data from the Los Alamos National Laboratory, Harvard researchers working in conjunction with the STAT news website estimated the minimum number of COVID-19 tests necessary to allow for easing stay-at-home restrictions in each state. Using different methods, two researchers each arrived at a monthly target of about 45 tests per 1,000 people—but cautioned that test volumes should reflect regional outbreak severity. The figure endorsed by the White House is approximately 30 monthly tests per 1,000 people, writes STAT reporter Sharon Begley.
Routine testing of all Americans is impossible, making it crucial to pinpoint a volume that is adequate for each community. Adequate local testing enables public health professionals to identify cases and their contacts in numbers great enough to substantially reduce transmission. The Harvard/STAT report illustrates that many states –including those that have begun to ease stay-at-home restrictions- are not testing enough to support effective contact tracing. Georgia, where many businesses have already been cleared to reopen, is currently testing just 4,000 of the approximately 10,000 daily tests suggested by the study.
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.”