More Than 40 Percent of New York Immune to the Coronavirus, Study Suggests

More than 40 percent of New York may be immune to the coronavirus, according to the authors of a study suggesting a second wave of COVID-19 may hit areas outside of the original metropolitan hotspots particularly hard.

The team used a mathematical model to carry out their research. This involved looking at the daily death counts in four countries, the U.S., U.K., Spain and Italy, and the hard-hit cities of New York, London, Madrid, and Milan and the surrounding Lombardy region. They also compared the timing of different interventions to stop the spread of the virus, as well as how the public responded, and the changes in the number of deaths.

When the coronavirus emerged, 100 percent of people were susceptible. As it spread, that figure went down. According to the team, the chunk of people in New York who are vulnerable to catching the virus is 59 percent of that in the rest of the U.S.

Overall, the authors found people in metropolitan areas were likely significantly less susceptible to the virus than the rest of the country. That is because cities were affected earlier, so case numbers grew for a longer period of time before measures to stop the spread were put in place when compared with the rest of the country.

Professor Peter Krüger, a physicist and data scientist at the University of Sussex, told Newsweek some groups, for instance those in neighbourhoods with inter-generational living arrangements or a high number of essential workers, will have a much higher than 40 percent previous infection rate, while other groups/areas will have a much lower than 40 percent rate. "But on average for the whole of New York it's 40 percent," he said.

The team also found that the drop in deaths after the initial peak was faster in metropolitan areas that were badly affected when compared with regions elsewhere in the respective countries.

Krüger said the fast decline means that the increase of immunity in a population "was having an effect independent of lockdown measures."

The team also considered a hypothetical scenario where restrictions were lifted, and predicted that infection rates in second waves would be smaller than in the initially affected cities, and bigger outside these locations where the first wave was weaker.

The study was submitted as a pre-print medRxiv meaning it hasn't been through the rigorous peer review process required to publish in scientific journals. Releasing studies this way enables scientists to prompt debate on a topic and are particularly useful during a fast-moving time like a pandemic when it is useful to release and discuss information quickly.

However, some experts expressed some doubts about the work. John Edmunds, professor in the Centre for the Mathematical Modelling of Infectious Diseases, London School of Hygiene & Tropical Medicine, who did not work on the study, said in a statement: "The authors suggest that significant numbers of people in London, Madrid and New York may be immune. There is, however, a much more direct and reliable way to estimate the levels of immunity in populations; that is by taking a representative sample of the population and testing for specific antibodies against SARS-CoV-2 (the virus that causes COVID-19) in their blood."

Edmunds said such studies on England "do indeed reveal that the level of immunity tends to be higher in London than elsewhere, however, they also show that the level of immunity—even in urban centres—remains relatively low."

Matt Keeling, professor of populations and disease at the U.K.'s University of Warwick who did not work on the paper, said the study was "interesting" but said he was "skeptical of the results."

Keeling said the issue lies in whether the earlier and quicker decline in cases seen in major cities is due to fewer people being susceptible or less social mixing.

He said: "While we would all like to believe that we are past the worst of this outbreak, the rising cases across many European countries would indicate that we are far from herd immunity and measures need to remain in force if we are to prevent a second wave even worse that the first."