In a unique study, influenza-infected college students shared a hotel room with healthy middle-aged volunteers for two weeks, yet no infections occurred. Researchers attribute this to limited coughing, good ventilation, and participants' age. The findings underscore the role of airflow and masks in preventing flu spread.
Researchers from the University of Maryland conducted an experiment in a quarantined Baltimore-area hotel floor, placing five college students with confirmed influenza alongside 11 healthy middle-aged adults. Over two weeks in 2023 and 2024, participants engaged in daily interactions like conversations, yoga, stretching, dancing, and sharing items such as pens, tablets, and microphones. Despite close contact, none of the healthy volunteers became infected, as confirmed by daily nasal swabs, saliva, blood samples, and air monitoring using the Gesundheit II machine.
The study, published January 7, 2026, in PLOS Pathogens, is the first controlled trial examining airborne flu transmission from naturally infected individuals. "At this time of year, it seems like everyone is catching the flu virus. And yet our study showed no transmission -- what does this say about how flu spreads and how to stop outbreaks?" said Dr. Donald Milton, a professor at the university's School of Public Health and an expert in infectious disease aerobiology.
Key factors included the infected students' high nasal virus levels but rare coughing, releasing only small amounts of virus. Dr. Jianyu Lai, who led the data analysis, noted, "Our data suggests key things that increase the likelihood of flu transmission -- coughing is a major one." Ventilation from a heater and dehumidifier rapidly mixed and diluted the air, reducing virus concentration. Middle-aged adults' lower susceptibility to flu also likely contributed, according to Lai.
Milton emphasized airborne transmission's role in flu spread and called for evidence-based infection controls. He advised using portable air purifiers to stir and clean air, and N95 masks during close, indoor encounters with coughers. The research highlights ongoing needs amid seasonal flu's global toll: up to 1 billion infections yearly, with the current U.S. season reporting 7.5 million cases, 81,000 hospitalizations, and over 3,000 deaths.
The team, including collaborators from institutions like Icahn School of Medicine at Mount Sinai and the University of Hong Kong, received funding from sources such as the NIAID and the Balvi Filantropic Fund.
