New York Starts 'Aggressive' Coronavirus Antibody Testing In Quest To Reopen Economy

Enlarge this image toggle caption Hannah A. Bullock, Azaibi Tamin/AP Hannah A. Bullock, Azaibi Tamin/AP

New York has begun "the most aggressive" statewide antibody testing to help determine how much of the population has been infected by and recovered from the coronavirus — a step health officials say is essential for reopening the economy.

Gov. Andrew Cuomo said Monday that state Department of Health officials plan to randomly select 3,000 people for tests that will look for indications that their bodies have fought off the virus, even if they were never tested or showed any symptoms.

"Any plan to start to reopen the economy has to be based on data and testing, and we have to make sure our antibody and diagnostic testing is up to the scale we need so we can safely get people back to work," Cuomo said in a statement, adding that the testing would be done "in the most aggressive way in the nation."

Cuomo noted that Germany — with a population of 83 million to New York's 19.5 million — used the same sample size for its antibody testing survey.

He said the results will provide "the first true snapshot of exactly how many people were infected by COVID-19 and where we are as a population and will help us to reopen and rebuild without jeopardizing what we've already accomplished."

Despite some slowing in the rate of diagnosed COVID-19 cases in New York, the state still makes up about a third of reported cases across the country. As of Monday, officials reported 252,595 cases in the state's 62 counties. The disease has killed more than 18,000 people in the state so far, accounting for 45% of U.S. deaths related to the virus.

Cuomo said the "large-scale antibody testing will help determine the percentage of the population that is now immune to the virus."

But, as NPR's Richard Harris reported, "Scientists do not know whether people with antibodies are definitively protected from the disease and, if so, for how long."

Last week, South Korean health officials announced they identified 163 people — more than 2% of the country's 7,829 patients — who tested positive for COVID-19 after making a full recovery. Those people are now back in isolation.

Dr. Jordan Laser, a pathologist at Northwell Health on Long Island, N.Y., told NPR it would make sense to start testing health care workers. But, even in instances where people may show that they have developed antibodies, Laser said they should still take precautions.

"Definitely don't use these tests to change your practices in terms of personal protective equipment," he said.

"Definitely do not become more comfortable in doing your job in taking care of COVID patients. It really would be more of a psychological benefit."

As more municipalities, businesses and health institutions begin to conduct large-scale blood tests to detect past exposure, questions about their efficacy have surfaced.

Currently, the tests on the market do not need approval from the U.S. Food and Drug Administration, and there are dozens of manufacturers making versions that claim to be more than 90% accurate. But the margin of error on false positives in many of the tests is too high for an accurate representation of the number of people who have been infected by the disease.

The White House Coronavirus Task Force, which has set an informal standard for the new tests, placed a limit of no more than 10 false positives per hundred.

"If you were to use a test that meets that standard, though, in a population where only 1% of the population has been infected, a positive result would actually be wrong a shocking amount of the time — like nine times out of 10," Harris reported.