A group of volunteers spent several days holed up in a small hotel room with actively infected people. influenza. They played games, shared things, and exercised together in an environment designed to promote health. virus Spread it. Still, not a single person was caught. influenza.

The unexpected discovery came from a well-designed study that aimed to answer a fundamental question: How does influenza actually spread?

Influenza, the virus that causes influenza, is known to spread through aerosols (tiny droplets) released when an infected person coughs, sneezes, or even coughs. breathing normally. It can also be transmitted from person to person through contaminated surfaces such as door handles or phones, which is known as fomite transmission.

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How efficiently the virus spreads several factorsThe amount of virus that infected people shed, the temperature and humidity of the room, the distance between people, etc.

To find out which of these factors is most important, researchers at the University of Maryland in the US Real-world transmission experiments Using people who had the flu naturally.

They assembled a group of participants in a hotel room and mixed patients with active influenza infection (called donors) with uninfected volunteers (called recipients). The goal was simple: to see if influenza could spread under conditions designed to promote infection.

Despite close contact over several days, not a single person became infected.

This approach previous research In this study, healthy volunteers were intentionally infected with influenza for research purposes. By using naturally infected “donors,” the researchers hoped to better reflect how influenza spreads outside the lab.

Two versions of the experiment were performed. In one example, one donor shared a room with eight recipients. The other was shared by four donors with three recipients. Donor age ranged from 20 to 22 years, and recipient age ranged from 25 to 45 years.

The room was maintained at temperature and humidity levels considered favorable for influenza transmission: 22 °C to 25 °C and 20% to 45% humidity. Before separating participants, the researchers intentionally lowered ventilation and poor air quality by blocking major uncontrolled air passages, such as leaking windows, doors, and fan coil units.

Participants spent hours together in a small space over three to seven days. They played card games up close, took dance and yoga classes, and passed out shared items like markers, microphones, and tablet computers.

The researchers monitored infection by measuring virus levels in the donors’ breath, saliva, and mouth swabs. Shared property and indoor air were also tested for virus particles. Participants recorded symptoms, including coughing, sneezing, headaches, and other common signs of the flu.

Reason for failure to send

Active influenza infection was confirmed in several samples from donors. However, none of the recipients tested positive. A few people reported mild symptoms, such as headaches, but none had clear evidence of influenza infection.

The researchers cited three main reasons why no infections occurred: low virus shedding from the donor, partial immunity in the recipient, and the way the air in the room was circulated.

Children are thought of as promote the spread of influenzaHowever, only adults participated in this study. The adult donors who participated in the experiment shed relatively small amounts of virus. This may reflect the strain they were infected with, their age, or the fact that they showed few symptoms. Few coughs or sneezes were observed, so the amount of virus entering the air is likely limited.

Recipients may also have been less susceptible. They have all been through many flu seasons, some had received a flu shot in the previous year, and one had received a vaccination this season. This prior exposure may have given them some background immunity.

Temperature and humidity were set to facilitate transmission, but high levels of air recirculation by fans may have disturbed clouds of virus-laden air. Rather than remaining around the donor, these plumes were broken up and diluted, potentially reducing the amount of virus the recipient inhaled.

Taken together, these findings point to coughing and sneezing as key factors in the spread of influenza, especially from people who shed large amounts of virus, sometimes described as “the flu.” super spreader. Immunity of exposed people and air movement in indoor spaces also appear to be important.

This study does not suggest that influenza is harmless or that it is difficult to spread. Every year, There are millions, perhaps billions, of cases worldwide.there is strong evidence of aerosol transmission play a central role. Rather, it shows that the conditions that allow influenza to spread are more subtle than simply sharing a room with an infected person.

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Not everyone sheds the virus at the same level, and not everyone is equally vulnerable. Aerosol spread is most likely to occur when coughing or sneezing, so people with these symptoms should isolate as much as possible and wear well-fitting masks to reduce the release of virus into the air. Good ventilation and air circulation is especially important in small, poorly ventilated spaces.

When in doubt, it’s safest to assume you can get or spread the flu and follow public health guidance, such as getting vaccinated and using masks when appropriate.

conor meehanAssociate Professor of Microbial Bioinformatics, Nottingham Trent University

This article is republished from conversation Under Creative Commons License. please read original article.