One in five people tested in New York City were found to have antibodies to Covid-19, according to new preliminary results from the New York's "aggressive" statewide antibody testing.
If these results hold water and reflect the whole population, they suggest that up to 2.7 million New Yorkers have already encountered SARS-Cov-2, the coronavirus that causes Covid-19, perhaps without even knowing they were infected.
Speaking at a press conference on Thursday, Governor Andrew Cuomo said 21.2 percent of people in New York City tested positive for Covid-19 antibodies during the state survey.
New York started rolling out its statewide antibody testing on Monday, April 20, and has already seen over 3,000 people randomly tested in public for antibodies to SARS-Cov-2 from 40 locations in 19 counties across the state.
Statewide, around 13.9 percent of people tested positive for having the antibodies, suggesting about 1 in 7 people in the state of New York have been infected with the virus. The rate was just under 17 percent on Long Island, nearly 12 percent in Westchester and Rockland Counties, and less than 4 percent in the rest of the state.
However, Governor Cuomo added that further testing needs to be carried out to see if they reflect the whole population. It also remains unclear whether people with the antibodies have any real immunity to the infection.
"The surveys were collected at grocery stores, box stores, et cetera. That's important,” said Cuomo. “These are people who are out and about shopping. They were not people who are in their home. They are not people who are isolated.”
“It means you're testing people who, by definition, are out of the home and not at work. What does that mean? I don't know, but that has to be a factor that's taken into consideration,” he added.
Dr Demetre C Daskalakis, the deputy commissioner for the city's Division of Disease Control, has also warned that the state’s antibody tests “may produce false negative or false positive results,” indicating the results may include some erroneous results.
With that said, the current antibody tests (as flawed as they may be at present) are still a powerful tool for understanding the current outbreak. Most notably, it can be used to calculate the death rate of this virus amongst all who were infected. “The testing also can tell you the infection rate in the population – where it’s higher, where it’s lower – to inform you on a reopening strategy,” added Cuomo.
With at least 263,260 confirmed Covid-19 cases, New York has been the worst-hit locality in the world so far, although early studies are also suggesting there’s a similar picture over in California when it comes to antibodies.
Preliminary antibody testing results suggest infections of Covid-19 are far more widespread – and the fatality rate much lower – in LA County than previously thought. The results imply that between 2.8 to 5.6 percent of the Californian county’s adult population has antibodies and has already encountered the infection.