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The coronavirus has been detected in air pollution particles by scientists investigating whether this could allow it to be transported over longer distances and increase the number of people infected.
The work is preliminary and it is not yet known whether the virus remains viable in contaminating particles and in sufficient quantity to cause disease.
Italian scientists used standard techniques to collect samples of outdoor air pollution at an urban and industrial site in the province of Bergamo, and identified a highly specific gene for Covid-19 in multiple samples. Detection was confirmed by blind testing in an independent laboratory.
Leonardo Setti of the University of Bologna in Italy, who led the work, said it was important to investigate whether the virus could be transmitted more widely by air pollution.
“I am a scientist and I am concerned when I don’t know,” he said. “If we know, we can find a solution. But if we don’t know, we can only suffer the consequences. “
Two other research groups have suggested that air pollution particles could help the coronavirus travel further in the air.
Statistical analysis by Setti’s team suggests that higher levels of particle contamination could explain higher rates of infection in parts of northern Italy before a blockade was imposed, an idea backed by another preliminary analysis. The region is one of the most polluted in Europe.
None of Setti’s team’s studies have been peer-reviewed, and therefore have not been endorsed by independent scientists. But experts agree that his proposal is plausible and requires investigation.
Previous studies have shown that airborne particles harbor microbes and that the airborne viruses that cause bird flu, measles, and FMD are likely to have been transported over considerable distances.
The potential role of air pollution particles is related to the broader question of how the coronavirus is transmitted. Large drops laden with cough viruses and sneezes from infected people fall to the ground in a meter or two. But the much smaller droplets, less than 5 microns in diameter, can stay in the air for minutes to hours and travel farther.
Experts are not sure if these tiny airborne drops can cause coronavirus infections, although they know that the Sars 2003 coronavirus has spread through the air and that the new virus can remain viable for hours in tiny droplets.
But the researchers say the importance of potential transmission in the air, and the possible role of the polluting particles, means that it should not be ruled out without evidence.
Infectious disease epidemics behave in different ways, but the 1918 flu pandemic that killed more than 50 million people is considered a key example of a pandemic that occurred in multiple waves, the latter being more severe than the first. It has been replicated, albeit milder, in subsequent influenza pandemics.
How and why multi-wave outbreaks occur, and how subsequent waves of infection can be prevented, has become a staple of epidemiological model studies and pandemic preparedness, which have looked at everything from social behavior and health policy up to vaccination and the accumulation of community immunity. , also known as collective immunity.
Is there evidence that the coronavirus is returning elsewhere?
This is being watched very carefully. Without a vaccine, and without widespread immunity to the new disease, the Singapore experience has raised alarm, which has seen a sudden resurgence of infections despite being praised for its early management of the outbreak.
Although Singapore instituted a strong contact locating system for its general population, the disease resurfaced in tight dormitory accommodation used by thousands of foreign workers with inadequate hygiene facilities and shared dining facilities.
Singapore’s experience, while very specific, has demonstrated the disease’s ability to return in force in places where people are very close, and its ability to exploit any weaknesses in established public health regimes to counter it.
What are the experts concerned about?
Conventional wisdom among scientists suggests that second waves of resistant infections occur after treatment and isolation capacity are depleted. In this case, the concern is that the social and political consensus behind the closings is being overtaken by public frustration and the urgent need to reopen economies.
The threat decreases when the population’s susceptibility to the disease falls below a certain threshold or when widespread vaccination is available.
Generally speaking, the proportion of susceptible and immune individuals in a population at the end of a wave determines the potential magnitude of a subsequent wave. The concern at the moment is that with a vaccine still months away, and the true rate of infection only guessing, populations worldwide remain highly vulnerable to both the resurgence and subsequent waves.
Peter Beaumont
Professor Jonathan Reid of the University of Bristol in the United Kingdom is investigating the transmission of coronaviruses in the air. “Perhaps not surprisingly, while suspended in the air, the tiny droplets can combine with urban background particles and be transported.”
He said the virus had been detected in small droplets collected indoors in China.
Setti said that small droplets between 0.1 and 1 micron can travel more when they are attached to pollution particles up to 10 microns than on their own. This is because the combined particle is larger and less dense than the droplet and can float through the air longer.
“The pollution particle is like a microplane and the passengers are the drops,” Sett said. Reid is more cautious: “I think the very small change in the size of the [combined] Particles are unlikely to play a role. “
Professor Frank Kelly of Imperial College London said the idea of contaminating particles carrying the virus further was interesting. “It is possible, but I would like to see this work repeated by two or three groups.”
Another expert, Professor John Sodeau from University College Cork in the Republic of Ireland, said: “The work seems plausible. But that’s the end result right now, and plausible [particle] interactions are not always biologically viable and may have no effect in the atmosphere. “He said the normal course of scientific research could take two to three years to confirm such findings.
Other research has indicated correlations between increased Covid-19 deaths and higher levels of air pollution before the pandemic. Long-term exposure to dirty air is known to harm lung health, which could make people more vulnerable to Covid-19.
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