Areas of New York have recorded a nearly 70 per cent rate of immunity to Covid-19, in what scientists have described as “stunning” findings that suggest they could be protected from any second wave.
Some 68 per cent of people who took antibody tests at a clinic in the Corona neighbourhood of Queens received positive results, while at another clinic in Jackson Heights, 56 per cent tested positive.
The results, shared by healthcare company CityMD with the New York Times, appear to show a higher antibody rate than anywhere in the world, based on publicly released data.
The next closest is the Italian province of Bergamo, which recorded 57 per cent, followed by Alpine ski resort Ischgl, the site of Austria's biggest coronavirus outbreak, which reported 47 per cent.
Emergency doctors in New York told the Telegraph on Thursday that the rates confirmed what they had been seeing clinically in lower income areas of the city which had high minority populations.
Dr Daniel Frogel, a senior vice president for operations at CityMD, which plays a key role in the New York City’s testing program, suggested that some communities may have already achieved herd immunity.
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However, virologists cautioned that the results may not be representative of the general population as the testing was carried out at urgent care centres. They also warned that not enough data exists to conclude anything on herd immunity.
New York is among the hardest-hit cities in the world, recording some 222,000 cases and nearly 23,000 deaths to date.
Less affluent areas of the boroughs of Queens and the Bronx, which have a high proportion of Hispanic and black residents and lower-income "essential workers", have been worst affected.
It was reported on Thursday that a staggering 74 parishoners at one Roman Catholic church in Queens have died from the coronavirus.
Wealthier areas recorded much lower rates, according to CityMD data. For example, at a clinic in Cobble Hill, a mostly white and wealthy neighbourhood in Brooklyn, only 13 per cent of people tested positive for antibodies.
The results suggest higher-income neighbourhoods may bear the brunt of any second wave to hit the city.
CityMD administered about 314,000 antibody tests in New York City, as of June 26. Citywide, 26 per cent of the tests came back positive.
New York State released its own figures at the height of the outbreak in early May, which showed the city's positive rate hovering around 20 per cent, while the Bronx on its own recorded a 34 per cent positive rate.
Angela Rasmussen, a virologist at Columbia University, called the high positive rate in Corona “a stunning finding.”
However, she said it would be a mistake to base public health decisions off antibody rates across a population.
The “magical number for herd immunity assumes that everyone infected has complete protection from a second infection. But what about people with partial protection?” she told the NYT. “They may not get sick, but they can get infected and pass it along.”
Prof Denis Nash, an epidemiology professor at the CUNY School of Public Health, added that he thought the concept of herd immunity was more applicable to closed populations, unlike New York City neighbourhoods.
“People from Corona, for example, who are testing negative will still be getting on the subways and going to other neighbourhoods where there may be more transmission," he told The Telegraph. “We have to be careful about applying simple epidemiological concepts to complex settings.”