A growing number of studies suggest that everything from lung size to how you pronounce certain letters could make some people flu superspreaders.
Superspreaders Aren’t Just a Covid-19 Phenomenon
In January 2020, British businessman Steve Walsh traveled internationally, visiting Singapore and France before returning to Brighton in the UK. During his trip, he contracted Covid-19 and unknowingly infected about a dozen people. Stories like this popularized the term “superspreader.”
Virologists, however, have long known that a small group of people often drive outbreaks of respiratory illnesses. Whether it’s Covid-19, flu, RSV, tuberculosis, or measles, the pattern holds: roughly 20% of infected people account for 80% of transmissions.
Viral Load Matters
The amount of virus in respiratory fluids can differ massively between people. Kylie Ainslie, an infectious disease researcher at the Peter Doherty Institute in Australia, says, “Some people have 10 million times more virus than others.” At peak infection, virus levels can reach up to a billion copies per milliliter.
But having more virus doesn’t automatically make someone a superspreader. Factors like speech patterns, mucus properties, and environmental humidity all play a role.
The Sickest People Spread the Most
Your stage of infection is critical. People release more infectious particles when their symptoms peak. A 2021 study on monkeys showed that Covid-19 infection increased the number of moisture particles exhaled from 3,000–5,000 per liter to 50,000–70,000. Each particle can carry 200–300 viral copies, allowing rapid transmission.
Smaller aerosols, less than five microns in diameter, travel deeper into the lungs. Chad Roy, a microbiology professor, explains that viruses may evolve to produce these smaller particles, which stay suspended in the air longer.
Speech Patterns Influence Spread
Superspreaders often emit more respiratory droplets while speaking or coughing. Studies show that overweight individuals produce more droplets, possibly due to shallower, faster breathing caused by excess chest and abdominal fat.
Interestingly, vowel sounds like those in “need” and “sea” create more breath particles than vowels in “saw” or “hot,” suggesting that even the way we talk can affect transmission.
Lung Size Plays a Role
Children are less likely to be superspreaders due to smaller lungs and airways. Among adults, lung size varies due to genetics, childhood activity, and environmental factors like pollution or asthma. Larger lung capacity means more air volume per breath, which increases the chance of spreading viruses.
