The Fred Hutchinson Cancer Research Center study, which is a preprint study and therefore has not been peer-reviewed, found that COVID-19 is typically passed through “super-spreader events” — and only 20% of those who test positive will transmit it to others.
The research team, led by Schiffer, Fred Hutch postdoctoral scientist Ashish Goyal and epidemiologist Bryan Mayer, used a computer model to compare the virus’ behavior to the flu.
COVID-19 largely “weaves its way” throughout populations by chance, according to an August 7 press release on the study, typically when someone who happens to be “briefly” highly contagious is in “the wrong place, at the wrong time.”
The study noted that, although people carrying COVID-19 can shed small amounts of the virus for several weeks, it isn’t enough to be contagious for more than one to two days.
The preliminary study was posted in medRxiv, an online journal and “preprint server” that allows for colleague discussion before the peer-review stage, the press release indicated.
“Schiffer stresses that his research is preliminary and subject to revision, but important enough to be presented to colleagues in the field for their consideration,” according to the press release.
Here’s what you need to know:
Super-Spreaders Happen When Someone Is at Their ‘Peak Contagious Point’
The Fred Hutchinson researchers “ran more than half a million computer simulations of possible ways to contract the coronavirus,” according to NBC affiliate King 5. They then compared those to actual data on how the virus is transferred.
Only a few of the simulations “matched real-world data,” King 5 reported.
People infected with COVID-19 are “usually contagious for fewer than two days,” the study found, often before they show symptoms or know they have the virus, according to King 5.
A “super-spreader” event is possible when a person at their “peak contagious point” happens to be in a crowd of people, King 5 reported. This can be even more detrimental if the infected individual is inside or around people without masks, the outlet said.
Schiffer said in the release that a small number of those infected can still be contagious for an extended period of time.
“The ethical thing to do as an individual is to walk around with the assumption that you’re infectious and contagious,” he expressed. “And that it’s your responsibility to protect the public. That doesn’t change at all.”
The Coronavirus May Be More Prone to Super-Spreading Than the Flu
The preliminary research found that both the flu and COVID-19 share a brief contagious period — but the latter may be more likely to super-spread.
This is “because of airborne transmission,” making the coronavirus much more “dangerous in crowded, confined spaces,” the press release indicated.
“Let’s say you have two people walk into a crowded, closed room, with poor ventilation,” Schiffer explained in the press release. “One of those people has influenza, and one has SARS-CoV-2. Both are unfortunately shedding at the highest viral load possible. Our model shows the person with influenza will likely expose far fewer people to their virus within that crowded environment than the person with SARS-CoV-2,” he added.
The idea of airborne transmission remains somewhat “controversial,” the press release said, even after the World Health Organization acknowledged there is a fair amount of evidence, Nature reported.
One of the First-Known U.S. Super-Spreader Events Happened at a March Choir Practice
Nearly 87% of the attendees contracted the coronavirus, the outlet reported, citing a Skagit County Public Health report published on the CDC website. The report categorized the practice as a “superspreader event.”
Three people were hospitalized and two died, King 5 reported.