(CNN) — A super spread event may be linked to about 20,000 COVID-19 cases in the Boston area, an investigator said Tuesday.
That event, a biotechnology conference attended by 200 people, in late February, is now recognized as a source of the spread of Covid-19 very early in the pandemic.
“Ultimately, more than 90 cases were diagnosed in people associated with this conference or their contacts, raising suspicions that a super-spreading event had occurred there,” the researchers wrote in their study.
Over-spread occurs when one or a few infected people cause a cascade of infectious disease transmissions.
The new study, which has not yet been peer-reviewed but was published on the online server medrxiv.org on Tuesday, involved analyzing the impact of early over-spreading events in the Boston area and provided “direct evidence” that over-propagation can profoundly alter the course of an epidemic.
“An unfortunate perfect storm”
The researchers, from the Broad Institute at MIT, Harvard in Cambridge and other institutions, carried out genetic analyzes of samples of coronavirus specimens in Massachusetts.
They sequenced and analyzed 772 complete genomes of the virus from the region. They found 80 introductions of the virus in Boston, mostly from other parts of the United States and Europe, and “hundreds of cases of major outbreaks” in various settings, including the conference.
The conference, which ran from Feb. 26-27, was a “perfect storm,” and the over-spread there may have been linked to about 20,000 cases, Bronwyn MacInnis, a researcher at the Broad Institute who worked on the study, told CNN. , in an email sent Tuesday.
“Many factors made the conference an unfortunate perfect storm as a super spread event. The fact that the virus was introduced at the conference was unfortunate, ”MacInnis wrote in the email.
“This is not a rigorous estimate, but it communicates the scale,” MacInnis added.
«If tens of thousands of people seem [una cifra] large, it is important to note that it is in the context of a pandemic that has infected tens of millions of people, “he added.
The timing was crucial. At the end of February, people were still not aware of the risk of the pandemic.
“The timing of it was critical: it was timed just when we were collectively beginning to appreciate the imminent threat of covid at home. If it had been a week later, the event would probably have been canceled, ”MacInnis wrote in the email.
“Also, as was the case early in the epidemic, it had the opportunity to spread widely before extensive testing, confinement, social distancing and masking capabilities became available,” he wrote.
‘The other critical factor was the population in which the virus landed: people who had come from many different places (including some where covid was already circulating), and who then returned home, often unknowingly, carrying the virus with them, ”he explained.
“A much greater understanding of the ease and speed with which this virus can be transmitted”
While the researchers did not identify the conference in their study, The Boston Globe said Tuesday it was an international gathering of leaders from the biotech company Biogen, at the Marriott Long Wharf Hotel in Boston.
“February 2020 was almost half a year ago and it was a period when general knowledge about the coronavirus was limited,” Biogen said in a written statement to CNN on Tuesday.
“We strictly adhere to current official guidelines. We would never have knowingly put anyone at risk. When we learned that several of our colleagues were ill, we did not know that the cause was covid-19, but we immediately notified public health authorities and took steps to limit the spread, “he explained.
The company noted in its statement that it joined a collaboration with the Broad Institute in April to share biological and medical data to advance knowledge about covid-19.
“The world today has a much greater understanding of the ease and speed with which this virus can be transmitted, and we are proud to contribute through this collaboration to the global effort to overcome covid-19,” he said.
Massachusetts Governor Charlie Baker said at a news conference Tuesday that he viewed the Biogen meeting in February as a “momentous event” in the coronavirus pandemic in the Boston area.
“I was actually criticized for saying a few months ago that the Biogen event was a momentous event regarding the crown here in the Commonwealth and I couldn’t put a number on it at the time,” Baker said.
“This is not an offense to anyone, but at that time, no one was wearing masks, no one was maintaining social distancing, no one was even behaving with concern about the presence of the virus. I mean all the rules of the game regarding that have changed, “said Baker. “It speaks of the power of that virus to pass from one person to another,” he added.
This new pre-print study also investigated the spread of the novel coronavirus in other settings in the Boston area, including a skilled nursing facility, where 85% of residents and 37% of staff tested positive, and a shelter for Homeless people, where the coronavirus was introduced seven times, including four that ended up generating clusters of cases, according to the study.
“Our findings repeatedly highlight the close relationships between apparently disconnected groups and populations: viruses [provenientes] international business travel spawned major outbreaks among the homeless, spread throughout the Boston area, and were exported to other national and international sites, ”the researchers wrote in the study.
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