NYC’s coronavirus outbreak spread from more European sources than first reported
The COVID-19 pandemic started earlier than previously thought in New York City and on Long Island by dozens of people infected mostly with strains from Europe, according to a new analysis, reported NYU Langone Health. The analysis also shows that most of the spread was within the community, as opposed to coming from people who had traveled.
Previous testing had detected the first case of the virus on March 3 before infections exploded throughout the metropolitan area, leading to 260,600 positive cases by mid-May.
Led by NYU Grossman School of Medicine researchers, the new study used gene testing to trace the origins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the pandemic virus, throughout the New York City region in the spring. It showed that the virus first took root in late February, seeded by at least 109 different sources that burst into chains of infection, rather than from a single “patient zero.”
Notably, the study authors say, more than 40 percent of people who tested positive had no known contact with another infected person before they contracted the virus.
“Our findings show that New York’s early screening test methods missed the onset and roots of the outbreak by several days at the minimum,” says study co-lead author Matthew T. Maurano, PhD, an assistant professor in the Department of Pathology at NYU Langone Health. “The work strongly suggests that to nip future outbreaks in the bud, we need a system of rapid, plentiful real-time genetic surveillance as well as traditional epidemiologic indicators.”
The investigators also found that more than 95 percent of New Yorkers with COVID-19 had a strain of the virus with a mutation that may make it easier to transmit to others. This finding, Dr. Maurano says, helps explain why the virus spread so aggressively in New York, even when accounting for the city’s high population density.
In gene sequencing, researchers compare small snips of genetic code to identify mutations that are only found in a particular strain of the virus. These “flags,” Dr. Maurano says, can then be used to track how the strain has spread over time, similarly to tests used to trace ancestry in people. Experts have previously used this technique to follow outbreaks of influenza, methicillin-resistant Staphylococcus aureus (MRSA), and Ebola, among other infections.
The new study, published in the journal Genome Research, is the largest effort to date to trace the COVID-19 pandemic using gene sequencing, according to Dr. Maurano. The study revealed that the genetic codes of the virus in New York more closely matched those of strains from Europe or other U.S. states rather than those from China, where the virus originated. In addition, some of the early chains of infection from person to person ran at least 50 people long.
