You know the type: the maskless man in the restaurant who won’t stop blowing his nose and hacking indiscriminately, apparently nonplussed by the pandemic.
It’s not just you.
A study newly published to research preprint site medRxiv reviewed so-called super-spreaders—who pass on a virus to nine or more others—of three majorcoronaviruses, named for their crown-like appearance under a microscope.
They looked at SARS, MERS, and, obviously, COVID-19. You probably remember the SARS—severe acute respiratory syndrome—and MERS—Middle East respiratory syndrome—outbreaks from the early 2000s and early 2010s, respectively.
The study found that the most typical super-spreader was a male age 40 or older, when it came to SARS and MERS, at least—so, yeah, the guy at the restaurant.
When it came to COVID, the most typical super-spreader was an adult of any age, from 18 to 91 years of age—not very specific. The study’s authors acknowledged their struggle gleaning demographic data from journal articles about super-spreaders and called on researchers to publish outbreak reports with “anonymized but useful” demographic data to fuel further research into the profile of such people.
The authors did find, however, that SARS and MERS super-spreaders were typically “very symptomatic” and later died in the hospital, while COVID super-spreaders usually had very mild illness.
How to identify a super-spreader
Why does identifying super-spreaders matter? The number of secondary cases of an illness stemming from a primary case—known as the “R naught value,” R0 value, Rt value, or basic reproduction number—determines how fast an epidemic spreads. Diseases with an R naught value of 1 or higher will continue to spread, often exponentially. Those with an R naught value of less than 1 will eventually die off.
A disease’s R naught value can change with time. Measles, one of the world’s most contagious diseases, has an approximate R naught value of around 18, according to the University of Nebraska Medical Center, while mumps has a value of around 12; polio and smallpox, 7; SARS, 4; Ebola and the 1918 flu pandemic, 2.
According to a Dec. 17 article in medical journal The Lancet, the R naught value of the original strain of COVID-19 was 2-5, while the delta variant had an R naught value of around 7. Omicron’s R naught value could be around 10, placing it up there among the world’s most contagious diseases.
But as important as the R naught value is, it doesn’t account for super-spreaders—and 10% to 20% of infected individuals may cause up to 80% of all cases, according to a June 2020 article in Nature. Thus, identifying potential super-spreaders, and super-spreader events, is super important in the battle against COVID-19 and other very communicable diseases.
Typical super-spreader traits
A June 2020 article published in the Indian Journal of Public Health found that super-spreaders often have one of more of the following qualities:
- often visit, or work in, crowded places.
- work in jobs that require frequent travel, perhaps as religious leaders, or restaurant, hotel, or hospital staff members.
- live or work in a confined space.
- take risks and may purposefully disregard instructions or quarantine.
- attend public or religious gatherings.
It cited the case of a 36-year-old Austrian bartender who worked at a popular ski resort in 2020. He was thought to have infected about 1,000 individuals from Austria, Iceland, Germany, Norway, and Denmark, helping to perpetuate the spread of COVID throughout Europe.
“An epidemic containment strategy needs to include early identification of super-spreaders to limit an explosive growth,” the article stated.
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