When several people with the flu share a closed room with others in perfect health for long hours, the spread of the virus seems inevitable. However, a recent experiment demonstrated that no infection occurred despite sustained proximity. This unexpected result challenges certain assumptions regarding the transmission of respiratory diseases.
To achieve this observation, scientists recreated this situation in a hotel in the Baltimore area. For two weeks, five students with the flu and eleven healthy volunteers conducted daily activities together, such as conversations and yoga sessions, in a confined space. This method aimed to mimic real social interactions while controlling environmental conditions.
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The lack of transmission is explained by several factors. The sick participants coughed very little, which limited the amount of virus released into the surrounding air. Furthermore, the room was equipped with a heating and dehumidification system that rapidly mixed the air, thereby diluting the viral particles present. These elements created a less conducive environment for contamination.
The age of the volunteers may also have influenced the results. Middle-aged adults, like those involved in the study, are often less susceptible to the flu than young adults. This difference in natural susceptibility may have helped reduce the risk of infection.
These observations offer concrete leads for prevention. In indoor spaces where air circulation is poor, the risk of contracting the flu increases. Ensuring good ventilation, for example with air purifiers, can therefore help protect occupants. Wearing a mask, especially an N95 type, remains an effective measure during close contact with a person showing symptoms.
The study was published in
PLOS Pathogens and relies on rigorous monitoring. Each day, nasal samples, saliva, and exhaled air were collected using specialized devices. This method allowed precise measurement of viral exposure and confirmed the absence of infection in the healthy participants, strengthening the reliability of the data.
Understanding how the flu is transmitted is important for public health. Every year, this disease affects millions of people worldwide, leading to hospitalizations and deaths. Strategies based on better air quality management could help limit the impact of seasonal epidemics, thus offering additional tools for collective protection.
The role of ventilation in dispersing viruses
Ventilation refers to the movement of air in an enclosed space. When air is stagnant, viral particles exhaled by an infected person can remain suspended and accumulate, increasing the risk for other occupants. On the other hand, good air exchange dilutes these particles and evacuates them outside.
Systems like air purifiers or simply opening windows promote this process. They create currents that mix the air, thereby reducing the concentration of viruses in the environment. This approach is particularly useful in public places where people gather, such as offices or schools.
Effectiveness depends on several factors, such as airflow rate and room size. Appropriate ventilation standards can therefore play a key role in preventing respiratory infections, complementing other measures like wearing masks or vaccination.