The main route of spread of the coronavirus is “aerosols” that people with COVID-19 – with or without symptoms – can emit when talking, coughing, shouting, singing or exhaling and can be suspended in the air. For this reason, closed spaces tend to support higher concentrations of aerosols and become an environment with a higher risk of infection when people with infections occur.
Now, a study conducted in the United States with a special machine has found that one can quantify and compare the particles exhaled by people. People who have got COVID-19 from infection with alpha, delta and omicron variants of the coronavirus may expel the virus in higher amounts than people infected with other variants.
Also researchers led by Donald Milton of the University of Maryland’s School of Public Health’s Institute for Applied Environmental Health, It has been found that people who get COVID-19 after vaccination and even after a booster dose, continue to release the virus into the air. it is worth clarifying that Vaccination, including a booster dose, is recommended because it prevents people who have been exposed to the coronavirus from developing or dying of serious illness.
The scientists’ work with the machine was published on the preprint server medrxiv And not yet peer reviewed. said co-author Kristen Coleman, who researches emerging infectious diseases at the University of Maryland in College Park. study evidence means people should “Press governments to invest in improving indoor air quality by improving ventilation and filtration systems.”
For the study, Coleman and his colleagues included 93 people who were infected with the coronavirus between mid-2020 and early 2022. The participants’ infections were caused by variants including the alpha variant, which emerged in late 2020, and later the Delta and Omicron variants. All participants with these last two types were fully vaccinated before becoming infected with the virus.
Infected people stood in front of a cone-shaped device and sang and shouted – accompanied by inevitable coughs and sneezes – for 30 minutes, while an attached machine collected the particles they expelled.
To study The researchers used a machine called the “Gesundheit-II”. This technology allows the separation of fine droplets of “aerosols” of 5 micrometers or less in diameter, Which can remain in the air and leak through clothing and surgical masks.
The team found that participants infected with the alpha, delta and Omicron variants emitted significantly more viral RNA upon exhalation than those infected with the other variants. Among them are a strain found in Wuhan, China in 2020 and variants that are not associated with low transmissibility, such as gamma, which emerged in late 2020, affecting South America with a wave of cases in the fall of 2021.
Delta and . for participants with Omicrons, their finer sprays contain on average five times the amount of virus found in their larger thicker sprays, The team also cultured the cells with aerosol samples in the laboratory and found that four samples, each from a participant with a delta or omicron, infected the cells.
“The virus taken out is not always contagious”, clarified the magazine Nature Study co-author Jianyu Lai, an epidemiologist at the University of Maryland, and the samples’ ability to infect laboratory cells means that viral RNA from exhaled aerosols can spread disease.
Malin Alsved, an aerosol technology scientist at Lund University, Sweden, commented on the study: “I’m a little worried that they mix everything up [aerosoles] Respiratory: Their sample has breathing, speech, screaming, coughing, even sneezing. But co-author Coleman said the team combined the respiratory samples to mimic a real-life setting, such as being in a restaurant.
The study also showed that there is inter-individual variation in the amount of virus removed, ranging from undetectable levels to those associated with “superspreaders”. For example, an Omicron-infected participant inhaled 1,000 times more viral RNA through fine aerosols than the maximum levels seen in those infected with alpha or delta. The researchers say the explanation for these discrepancies remains a mystery, but may be related to biological factors such as a person’s age. Behavior may also play a role: The person coughs more often than others.
If the new variants have a high risk of superspreading, it could affect their spread in COVID-19 cases. The team noted that people infected with the coronavirus exhale much smaller amounts of viral RNA than people infected with the flu, a comparable airborne illness. This shows that the coronavirus can lead to variants that transmit even more viruses, “It’s a matter of concern,” Alswede said.
The research showed that the three variants that win the infection race Alpha, Delta and Omicron “leave the body more efficiently when people speak or shout than the first variant of the coronavirus”. John Volkens, a public health engineer at Colorado State University in Fort Collins, who was not involved in the study.
To protect against COVID-19, today “there is no way that keeps us safe from COVID-19. Many things must be done to reduce the risk,” said Jose Luis Jiménez, a Spaniard, a scientist and scientist in the United States. Professor of Chemistry at the University of Colorado Boulder. This expert recommended adopting virologist Ian McKay’s Swiss cheese model. This model involves individual actions which, if combined together, reduce risk. Which includes vaccination, ventilation of the environment, use of chinstrap, hand washing, 2 meters distance, isolation in cases where a person has the infection, among others.