The coronavirus is far from the only virus that spreads through the air

Through intensive research, we changed the way SARS-CoV-2 spread during the pandemic. And now we seem to have to do the same for completely different viruses.

There have been many abuses and doubts about whether diseases can spread through the air. For example, the WHO has only recognized since last May that the coronavirus is mainly spread through the air. But according to researchers in a new study The coronavirus is far from the only virus that can be transmitted to others through the air. And so they say we need to review the mode of transmission of many other viruses.

Handover

Until recently, it was believed that most respiratory pathogens spread through large droplets exhaled by a contagious coughing or sneezing person, or by touching contaminated surfaces. Many measures to contain the coronavirus, for example, are based on this. But a growing body of studies, meanwhile, has shown that many respiratory pathogens — including SARS-CoV-2 — can spread through tiny, virus-laden aerosols, which remain suspended in the air for much longer.

Indoors

In a new study, the researchers took a closer look at the transmission route of the coronavirus. And they also come to one and the same conclusion: the coronavirus mainly spreads through the air; not via surface contact or via large droplets. The small droplets can especially accumulate indoors and linger for hours without proper ventilation. That way, the shared air is inhaled by everyone in the same room. “This inhalation transmission of virus-laden aerosols has long been underreported,” said study researcher Chia Wang. “It’s time to rethink conventional paradigms by taking precautions. That way we can protect ourselves from this transmission route.”

particles

It was previously thought that relatively large and heavy droplets released when someone breathes, talks, sings, screams, coughs or sneezes, fall quickly to the ground and thus only remain in the air for a short time. Now we know that the smallest aerosols that are released can be smaller than five micrometers. These can linger in the air longer, travel greater distances and penetrate deeper into the airways. “In addition, studies have shown that there are more viruses in aerosols smaller than five micrometers,” emphasizes researcher Josué Sznitman. And so you can get infected not only at a short distance from an infected person, but also over longer distances.

Stages involved in airway transmission of respiratory viruses. Image: Wang et al.

It means that the current pandemic has made us look very differently at how the coronavirus spread. And that means that we should do the same better for completely different viruses. Scientists argue that the coronavirus is really not the only virus that spreads through the air. For example, several respiratory pathogens are known to spread through aerosols that piggyback on air currents for a long time and can travel much greater distances. According to the researchers, it is therefore not only about the current spreading coronavirus, but also about the MERS virus, the measles and rhinoviruses that cause the common cold. These can all spread through aerosols that accumulate in the indoor air and remain suspended. And that way, someone who unsuspectingly inhales them can become infected.

Ventilation

Scientists now state that airborne contamination is likely a much more important and even dominant route of transmission for most respiratory diseases. It means that many more respiratory pathogens are spreading this way than previously thought. And so something has to be done about it, the research team argues. By ensuring adequate ventilation rates, filtration and avoiding recirculation, the transmission of infectious, virus-laden aerosols through the air can be drastically reduced, they say. “For example, you can monitor CO2 using portable meters to check whether the ventilation is adequate,” suggests researcher Jose-Luis Jimenez. These meters indicate how much exhaled air accumulates in the room, so that we can rigorously reduce the transmission rate of diseases.

Plexiglass

The researchers advise against using Plexiglas, which is now often used at cash registers or counters. “These hinder a good ventilation system and can actually cause higher exposure,” said researcher Linsey Marr. “They are not recommended except for short, face-to-face interactions. But even then, it’s better to wear masks because they help stop aerosols, while Plexiglas just redirects them.”

Triple strategy

According to the researchers, a threefold strategy is necessary: ​​vaccination, masks and ventilation. “A single strategy is unlikely to be strong enough to eliminate transmission of emerging corona variants,” concludes Seema Lakdawala. The researchers therefore argue for better precautions to combat contaminated aerosols. This can be done, for example, by wearing mouth caps with a better fit, improving indoor ventilation systems and avoiding recirculation of polluted indoor air, for example by installing air filters that can effectively remove particles from the air.

The scientists also advise better mapping the transmission route of other viruses. Because if there’s one thing we’ve learned from the current pandemic, it’s that we’ve significantly underestimated the airborne transmission route. According to the researchers, there is a real need to provide people with clean air, free of pathogens. “The pandemic has highlighted ways to make the right changes to safely enter the post-epidemic era,” Wang said. “The precautions regarding aerosols will not only help reduce the transmission of respiratory infections through the air, but will also improve indoor air quality. Ultimately, it will result in health benefits that go far beyond the COVID-19 pandemic.”