At the beginning of February 2020, China blocked over 50 million people, hoping to hinder the spread of a new coronavirus. Nobody knew exactly how he was spreading, but Lidia Moraowska, an air quality expert at the Queensland University of Technology in Australia, did not like the clues he managed to find.
It seemed to her as if the Coronavirus was spreading in the air, transported by drops of difficulties exhaled by the infected. If this were true, then standard measures such as the disinfection of the surfaces and stay a few meters from people with symptoms would not be enough to avoid infection.
Dr. Moraowska and his colleague, Junji Cao at the Chinese Academy of the Beijing Sciences, have drawn up a desperate warning. By ignoring the diffusion in the air of the virus, they wrote, it would lead to many more infections. But when scientists sent their comment to medical magazines, they were rejected over and over again.
“Nobody would listen to,” said dr. Moraowska.
It took more than two years for the World Health Organization to officially recognize that Covidid spread in the air. Now, five years after Dr. Moraowska has started playing the alarm, scientists are paying more attention to how other diseases can also spread in the air. At the top of their list there is avian influence.
Last year, the disease control centers recorded 66 people in the United States who were infected with a strain of avian influenza called H5N1. Some of them most likely fell ill, handling birds full of viruses. In March, the Department of Agriculture discovered the cows that were also infected with H5N1 and that animals could pass the virus to people, possibly through droplets spilled by milking machinery.
If avian influenza acquires the ability to spread from person to person, he could produce the next pandemic. So some influence experts are anxiously monitoring the changes that could make the air virus, drift in small droplets through hospitals, restaurants and other shared spaces, where its next victims could inhale.
“Having such tests is really important in advance, so as not to end up in the same situation in which Covidid emerged, where everyone was climbing to understand how the virus was transmitted,” said Kristen K. Coleman, an infectious expert in Diseases at the University of Maryland.
Scientists discussed how the flu viruses have spread for over a century. In 1918, a influence voltage called H1N1 brushed the world and killed over 50 million people. Some American cities treated it as a disease dispersed in the air, which requires masks in public and opening of windows in schools. But many public health experts were convinced that the influence spread largely by direct contact, such as touching a contaminated door knob or being sneezing or tossing.
H5N1 came to light for the first time in 1996, when it was detected in wild birds in China. The virus infected their digestive traits and spread through their feces. Over the years, the virus has spread to millions of chickens and other cultivated birds. Even hundreds of people got sick, mainly from the management of sick animals. Those victims developed H5n1 infections in their lungs that often proved fatal. But the virus could not move promptly from one person to another.
The threat of an outbreak of H5n1 in human populations pushed scientists to look closely how the flu viruses spread. In an experiment, Sander Herfst, a virologist from the University of Erasmus Rotterdam in the Netherlands, and his colleagues tested if H5n1 could spread among the ferrets in cages positioned at four inch distance.
“Animals cannot touch each other, they cannot lick each other,” said dr. Herfst. “So the only way to transmission is through the air.”
When Dr. Herfst and his colleagues sprayed the H5n1 viruses in the Nostrums of the ferrets, they developed lung infections. They have not spread the viruses in healthy ferrets in other cages.
But Dr. Herfst and his colleagues discovered that some mutations have allowed H5n1 to become dispersed in the air. Genetically modified viruses that brought those mutations spread from one cage to another in three out of four tests, making healthy ferrets sick.
When scientists shared these results in 2012, an intense debate broke out on the fact that scientists should intentionally try to produce viruses that could start a new pandemic. However, other scientists have followed the research to understand how these mutations have allowed the influence to spread in the air.
Some searches have suggested that viruses become more stable, so that they can bear a journey into the air inside a drop. When another mammal sticks the drop, some mutations allow viruses to cling to the cells in the upper airways of the animal. And still other mutations can allow the virus to thrive in the fresh airways temperature, creating many new viruses that can be exhaled.
The monitoring of the influence between humans proved to be more difficult, despite about a billion people get a seasonal influence every year. But some studies have indicated the transmission in the air. In 2018, the researchers recruited university students who suffered influence and breathed them in an air sampler in the shape of a horn. Thirty -nine percent of the small droplets that exhaled transported vital influence viruses.
Despite these results, exactly as the flu spreads through air it is not yet clear. Scientists cannot offer a precise figure for the percentage of cases of influence caused by diffusion in the air compared to a surface contaminated as a handle.
“There is really a very simple knowledge,” said dr. Herfst.
During the flu season last year, Dr. Coleman and his colleagues made people sick with the influence in a hotel in Baltimore. The sick volunteers spent time in a room with healthy people, playing and speaking together.
Dr. Coleman and his colleagues collected the flu virus that floated in the room. But none of the non -infected volunteers fell ill, so scientists were unable to compare the frequency with which influence infected people in the air instead of in short -range cough or on virus surfaces.
“It is difficult to imitate real life,” said dr. Coleman.
While Dr. Coleman and his colleagues continue to try to define the spread of the influence, the influence on the bird is increasingly infected in the United States. Cats are also infected, possibly drinking raw milk or eating raw pet food.
Some influence experts are concerned that H5N1 is gaining some of the mutations necessary to become dispersed in the air. A virus isolated from a milk worker in Texas had a mutation that could accelerate his replication in airways, for example. When Dr. Herfst and his colleagues sprayed the ferrets with drops in the air that transported the Texas virus, 30 percent of animals developed infections.
“The workshops in the United States and all over the world are looking for if those viruses are approaching some something that could be very dangerous for humans,” said dr. Herfst.
It would be impossible to predict when – or although – the avian flu viruses will get the additional mutations necessary to quickly spread from person to person, said Seema Lakdawala, virologist at the EMIORY University. But with the virus that runs rampant in farms and so many people who are infected, the chances of evolution in the air are growing.
“What is shocking to me is that we are letting nature do this experiment,” said dr. Lakdawala.