Infections in closed spaces –

GENEVA (EFE).— The risk of influenza being transmitted from one person to another in closed spaces through aerosols (tiny droplets) that we expel when we cough or sneeze is higher when these come into contact with bacteria present in our respiratory tract, according to a study published yesterday.

The research, organised by the Federal Polytechnic School of Lausanne (EPFL), found that when droplets infected with influenza were placed on a flat surface, the viral load was 100 times higher and lasted longer when contaminated with bacteria that are present in the human respiratory tract.

The study, published in the Journal of Virology, explains that these bacteria act as protectors against the flu virus when it leaves the human body, as they make infected droplets “flatter.”

“This shape speeds up the evaporation and crystallization process of the salt in the droplet, allowing viruses to live longer in dry environments, such as indoor spaces in winter when the heating is on,” said EPFL researcher Shannon David, who led the study.

The expert warned that this protective function of bacteria is not taken into account in the models currently used to predict the spread of a virus in an enclosed space, so “the risk of contagion is probably being underestimated.”

In addition to the test on a flat surface, the scientists also measured the viral load of the droplets when they are suspended in the air and determined that the bacterial species with the greatest stabilizing effect are Staphylococcus aureus and Streptococcus pneumoniae, which commonly colonize the respiratory tract.

These findings, experts say, provide an important piece of the puzzle of how respiratory diseases are transmitted and open a new line of research to identify people who are potentially more contagious by carrying more protective bacteria in their respiratory tract.

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