Most coronavirus cases in New York came from Europe and not China or other Asian countries, shows study
The first confirmed COVID-19 cases of New York City were primarily from European and US sources, and not Asia.
This is according to a new analysis which traced the source of these cases and found that the pandemic in New York City predominately rose through untracked transmission between the US and Europe, with limited evidence to support any direct introductions from China, where the virus originated, or other locations in Asia.
The study — led by Icahn School of Medicine at Mount Sinai (ISMMS) researchers — also documented early community spread of SARS-CoV-2 (the virus that causes COVID-19) in New York City during that time.
Accordingly, researchers suggested that the virus was likely circulating as early as late-January 2020 in the New York City area. This underscores the urgent need for early and continued broad testing to identify untracked transmission clusters in the community, says the team.
With 159,937 cases and 7,067 deaths, New York is the epicenter of the pandemic in the US, according to a report. "The 1918 Spanish flu hit in 3 waves. We are only in the first wave. We can't assume that because we are seeing some positive signs this will be over soon or that additional waves won't hit. NYS will not underestimate this enemy," New York Governor Andrew Cuomo tweeted.
Knowing the time the virus came to New York and the route it took is essential for evaluating and designing effective containment strategies. Accordingly, the researchers sequenced 90 SARS-CoV-2 genomes from 84 of over 800 confirmed COVID-19 positive cases within the Mount Sinai Health System.
The team sequenced genomes from COVID-19 cases identified up to March 18. These cases were drawn from 21 New York City neighborhoods across four boroughs (Manhattan, Bronx, Queens and Brooklyn) as well as two towns in neighboring Westchester County.
(AP Photo/Mary Altaffer)
The analysis shows multiple independent but isolated introductions mainly from Europe and other parts of the US. In addition, clusters of related viruses found in patients living in different neighborhoods of the city provide strong evidence of community transmission of SARS-CoV2 in the city prior to March 18, says the study, a pre-print version of which has been published in medRxiv.
Only one of the cases studied was infected with a virus that was a clear candidate for introduction from Asia, and that virus is most closely related to viral isolates from Seattle, Washington, say experts.
A separate study by the NYU Grossman School of Medicine has made a strikingly similar observation. According to the experts, early data suggest that the novel coronavirus has been spreading in the New York City community for a couple of months and before testing started. "The particular genetic codes in most local viral samples indicate that they originated in Europe," says the analysis.
Analysis reveals 3 distinct variants of COVID-19
Experts have discovered three distinct strains of COVID-19, consisting of clusters of "closely related lineages" — which have been labeled 'A', 'B' and 'C'.
The team used data from virus genomes sampled from across the world between December 24, 2019, and March 4, 2020. The team from the University of Cambridge, UK, and the Institute of Forensic Genetics, Germany, among others, reconstructed the early "evolutionary paths" of COVID-19 in humans — as the infection spread from Wuhan out to Europe and North America — using genetic network techniques.
By analyzing the first 160 complete virus genomes to be sequenced from human patients, the scientists have mapped some of the original spread of the new coronavirus through its mutations, which creates different viral lineages.
The research team found that the closest type of COVID-19 to the one discovered in bats — type A, the "original human virus genome" — was present in Wuhan, but surprisingly was not the city's predominant virus type.
Mutated versions of 'A' were seen in Americans reported to have lived in Wuhan, and a large number of A-type viruses were found in patients from the US and Australia.
"Wuhan's major virus type, 'B', was prevalent in patients from across East Asia. However, the variant didn't travel much beyond the region without further mutations — implying a founder event in Wuhan, or resistance against this type of COVID-19 outside East Asia," say researchers in the study published in Proceedings of the National Academy of Sciences (PNAS).
The 'C' variant is the major European type, found in early patients from France, Italy, Sweden, and England. It is absent from the study's Chinese mainland sample but seen in Singapore, Hong Kong, and South Korea.
The researchers say that their genetic networking techniques accurately traced established infection routes: the mutations and viral lineages joined the dots between known cases. "Phylogenetic network analysis has the potential to help identify undocumented COVID-19 infection sources, which can then be quarantined to contain further spread of the disease worldwide," says Dr Peter Forster, lead author of the study from the University of Cambridge.