SARS-CoV-2 transmission: How important is ‘super-spreading’?

SARS-CoV-2 transmission: How important is ‘super-spreading’?

Written by Erika Watts on November 6, 2020 — Fact checked by Rita Ponce, Ph.D.

A new study suggests that COVID-19 super-spreading events are more common than originally believed. Limiting gatherings to 10 or fewer people could help prevent this issue.

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Scientists have spent the better part of the past year trying to make sense of the novel coronavirus, SARS-CoV-2, which causes the disease responsible for the ongoing pandemic.

As COVID-19 cases approach 49 million worldwide, researchers continue to study how the virus spreads in an effort to find ways of reducing the transmission.

A new study from researchers at the Massachusetts Institute of Technology (MIT), in Cambridge, examines the spread of COVID-19 in large gatherings. It shows that super-spreading events are more common — and have more impact on the overall spread of the virus — than previously thought.

In their study paper, published in Proceedings of the National Academy of Sciences, theresearchers explain that these events have an “outsized” role in virus transmission.

Stay informed with live updates on the current COVID-19 outbreak and visit our coronavirus hub for more advice on prevention and treatment.

‘Super-spreading events’ defined

On average, SARS-CoV-2 spreads from one person to two to three others. In some cases, the virus does not transmit. But it can pass to dozens of other people in a relatively short period.

A super-spreading event is a gathering where the virus transmits from one person to several others. The researchers behind the present study considered super-spreading to take place when at least six people acquired the virus.

One such event, a choir practice, took place in Skagit County, WA. Scientists tracked 53 cases of COVID-19 back to one person with a SARS-CoV-2 infection at the rehearsal.

Of the 61 people who attended the 2.5-hour event, 33 tested positive for COVID-19 and 20 others had probable cases.

Since COVID-19 primarily transmits through respiratory droplets, the choir practice was a prime environment for it to spread.

Some other notable COVID-19 super-spreading events include the White House’s Rose Garden event where 35 out of approximately 200 attendees acquired the virus and a birthday party in Westport, CT, where 20 of the 50 partygoers acquired the virus.


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