JTA — One year after COVID-19 first walloped Jewish communities in the United States, a scientific study has confirmed something that many in the communities have long believed: gatherings during the week of Purim served as superspreader events.

A paper published Wednesday in the Journal of the American Medical Association Network Open, a peer-review journal that is open to the public, concludes that the coronavirus was spreading widely in Orthodox communities across the country last spring around that Jewish holiday — before public health warnings were given about the dangers of large assemblies.

The paper was peer-reviewed, meaning that its conclusions have been scrutinized and accepted through a rigorous process. Now its authors — four Orthodox Jewish physicians who engineered a study of thousands of blood samples from Orthodox Jews who contracted COVID-19 spanning five states — say their paper has lessons as public health officials steer Americans through the pandemic’s next phase.

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“There should be specific recommendations for each religious and ethnic community,” said Dr. Israel Zyskind, a pediatrician in Brooklyn and one of the authors. “They should be culturally sensitive, which is not something we’ve seen with the pandemic, especially early on.”

Dr. Avi Rosenberg, a renal pathologist at Johns Hopkins University and another author of the paper, said for Purim in particular, “the guidance all came a week too late.”

“The mask mandate followed Purim, the national lockdown followed Purim, the announcement of COVID as a pandemic followed Purim,” he said.

The paper is the first publication to come out of a research project started by three Orthodox Jewish doctors who decided early in the pandemic to turn a tragic turn of events — the extensive spread of the coronavirus in Orthodox communities around Purim — into an opportunity to learn more about the virus through research. Through their project, which they called the “Multi-InstituTional study analyZing anti-CoV-2 Antibodies” — or the MITZVA cohort — they collected thousands of blood specimens that would go on to be used in 10 research labs for virology studies related to COVID in addition to their own paper published Wednesday.

For the originators of the MITZVA cohort, the findings are an embodiment of the good deed they hoped to bring about last spring and a corrective to some of the negative press that some Orthodox communities have received for violating of public health guidelines.

“The point of this whole effort was to make a ‘kiddush Hashem,’ to show we care about our neighbors,” Zyskind said, using the term for sanctification of God’s name. “And we came out by the thousands to do that.”

The most important finding in their paper, according to the authors, is in understanding how the timing of Purim and lack of public health guidance at that time allowed the disease to spread widely in Orthodox communities. The study found that the onset of symptoms in all five states they studied came within one week of each other, suggesting that the interconnectedness of Orthodox communities across states should be considered when responding to a pandemic.

Published just weeks before Passover, the paper’s argument for public health guidance tailored to religious communities is still relevant. With millions of Americans already vaccinated, many families are hoping to gather this year for Passover Seders following a year of Jewish holidays spent in isolation. But with most of the country still unvaccinated, the risks of gathering prematurely are significant for the unvaccinated.

A boy carries a box of matzos for Passover that he picked up from his synagogue in the Brooklyn borough of New York, March 26, 2020. (AP Photo/Mark Lennihan)

“Pesach is about to come and there’s an urge now that we’re a year into this that we should let things down,” Rosenberg said. “Knowing how we celebrate … the suggestion would be that the numbers are still quite high and, unless you are vaccinated or recently convalesced, to continue to temper celebrations across family units.”

The paper also suggests that the infection rates in Orthodox communities in the early stages of the pandemic were higher than in surrounding communities, something the authors attribute to the highly social nature of the Orthodox community. But while many in certain Orthodox communities came to believe that their communities had reached herd immunity by late spring and early summer, with many returning to normal life while experiencing few new infections, the data in the study shows that to be unlikely.

In New Jersey, the community with the highest percentage of positive antibody tests among the study samples, 32.5% of samples tested positive for antibodies.

“No value in the paper approaches herd immunity,” Rosenberg said.

In fact, the study also helped correct misconceptions some people had about their immunity status last spring.

“We learned in this process that a lot of people reported symptoms but they didn’t have serologic evidence of COVID,” Rosenberg said, meaning that people who thought they had had COVID and were unlikely to contract it again had not actually had COVID. The study also discovered antibodies in people who had not had any symptoms, pointing to asymptomatic cases.

The study first came together in the early days of the pandemic when Rosenberg reconnected with Zyskind, his former Brooklyn College classmate. The two were answering similar questions from members of their community about COVID and about policies for synagogues and schools. They soon started thinking about the possibility of doing research related to COVID within the Orthodox community and got in touch with Dr. Jonathan Silverberg, a dermatologist and epidemiologist at George Washington University, also a college classmate.

In this October 4, 2020, photo, two women walk with children during the Jewish holiday of Sukkot in the Borough Park neighborhood of the Brooklyn borough of New York. (AP/Kathy Willens)

They applied for approval from the Institutional Review Board to conduct a study and collected blood specimens over a two-week period in May. With the help of community organizations like New Jersey’s Lakewood Bikur Cholim, which provides food and other services to hospital patients and others dealing with medical issues, they were able to collect blood samples from 6,665 people in Orthodox communities in five states.

When Silverberg, Rosenberg and Zyskind were first envisioning a research project, they were hoping to conduct a prevalence study, which would indicate what percentage of a community had been infected with COVID. But the sample size needed for a prevalence study proved too large, so the trio retooled their approach.

They decided that each trial participant would fill out a detailed questionnaire about the onset of their symptoms (the questionnaire provided the English calendar dates for Purim and Passover as reference points), the severity of symptoms and how long they lasted. Then they would take two vials of blood from each participant, with one from each participant to be used for antibody testing and for the paper.

The other vials, as well as approximately 2,000 saliva samples taken from the same participants, would be sent off to 10 research labs for a range of virology studies related to COVID.

The three doctors say they are excited to finally publish the findings of their research nearly a year after it began. And with approximately eight studies currently in process using those samples, there are more papers expected in the coming months on subjects like the differences between T-cell immunity and antibody immunity and the detection of antibodies in saliva.

“There are now five other manuscripts in development with data from this cohort that are really groundbreaking,” Silverberg said. “It’s a credit to the Orthodox community and their efforts in coming out and helping put this all together.”