New York Gov. Andrew Cuomo said on Sunday that the state plans to roll out antibody testing this week to determine who has been infected with Covid-19, conducting the "largest survey of any state population that has been done."

Cuomo said the U.S. Food and Drug Administration approved the state's antibody test, which is designed to detect whether a person has developed the antibodies to fight Covid-19 and indicates they may be immune against the disease, and said the state will conduct "thousands" of tests this week.

"We'll take thousands of tests, antibody tests, over this next week all across the state to give us a real snapshot, a real baseline, of exactly how many people were infected by coronavirus and have the antibodies," Cuomo said. "So we'll have the first real statistical number on exactly where we are as a population."

The antibody tests will give the state its "first true snapshot" of how many people in the state have been infected with Covid-19, Cuomo said. Melissa DeRosa, secretary to the governor, later tweeted that the state antibody testing will begin on Monday and will sample 3,000 people.

https://twitter.com/melissadderosa/status/1251924079768199171

"We don't really know how many people were infected. How many people had coronavirus but self-resolved. We don't really know because we haven't been able to do testing on that large of scale," Cuomo said. "We're going to do that in the most aggressive way in the nation..."

States should institute a "robust testing program in place for at-risk healthcare workers, including emerging antibody testing," according to President Donald Trump's broad new federal guidelines to reopen the economy issued Thursday.

Researchers, many of whom are from Stanford University, published a study Friday that found Covid-19 could be far more widespread in Santa Clara County in Northern California than the official counts suggest.

"It adds to growing body of work that suggests a huge amount of cases that went undetected," John Brownstein, an epidemiologist at Boston Children's Hospital, said.

However, global health officials have recently questioned if antibody testing can accurately determine whether a person is immune to the disease. The World Health Organization issued a warning Friday saying there's no evidence serological tests can show whether a person has immunity or is no longer at risk of becoming reinfected.

"These antibody tests will be able to measure that level of serology presence, that level of antibodies, but that does not mean that somebody with antibodies" is immune, Dr. Maria Van Kerkhove, head of WHO's emerging diseases and zoonosis unit, said on Friday.

Dr. Mike Ryan, executive director of WHO's emergencies program, said scientists are also still determining the length of protection antibodies might give a person who has been infected with the coronavirus.