Though influenza (flu) and COVID-19 are both contagious respiratory illnesses, they are caused by different viruses. This CDC document highlights their similarities and differences.

The New York Times reporter Katherine J. Wu explains in a recent article that why coronavirus is more likely to ‘superspread’ than the flu. “The coronavirus (120 nanometers wide) virus can be a remarkably cosmopolitan traveler. Spewed from the nose or mouth, it can rocket across a room and splatter onto surfaces; it can waft into poorly ventilated spaces and linger in the air for hours. At its most intrepid, the virus can spread from a single individual to dozens of others, perhaps even a hundred or more at once, proliferating through packed crowds in what is called a superspreading event.”

There appears to be some evidence that some people spread more than others. Dr Shweta Bansal, an infectious disease ecologist at Georgetown University, told to the Times “this confluence of factors — a person in the wrong place at the wrong point in their infection — sets the stage for ‘explosive transmission’.”

There’s this small percentage of people who appear to infect a lot of people. Estimates vary from population to population, but they consistently show a striking skew: Between 10 and 20 percent of coronavirus cases may seed 80 percent of new infections. Other respiratory diseases, like the flu, are far more egalitarian in their spread.

Dr. Joshua Schiffer, Fred Hutchinson Cancer Research Center in Seattle (source: The New York Times)

• Why the Coronavirus Is More Likely to ‘Superspread’ Than the Flu
• Wrong person, place and time: viral load and contact network structure predict 4 SARS-CoV-2 transmission and super-spreading events
• How ‘Superspreading’ Events Drive Most COVID-19 Spread

In the Scientific American, Christie Aschwanden writes “As few as 10 percent of infected people may drive a whopping 80 percent of cases in specific types of situations. {..] As scientists have learned more about COVID-19, it has become clear that so-called superspreader incidents—in which one person infects a disproportionate number of other individuals—have played an oversized role in the transmission of the virus that causes the disease.”

These numbers mean that preventing superspreader events could go a long way toward stopping COVID-19.

Samuel Scarpino, Northeastern University (source: Scientific American)

To reduce the spread of the virus, it’s important to minimize exposure to those conditions that are conducive for spreading the virus such as crowded events, enclosed spaces and not following guidelines (mask wearing, social distancing and hand washing).