Researchers examined subjects during their Covid-19 infection. One of them coughed up 1,000 times more virus than other subjects with Delta or Alpha.
Whether you contract the coronavirus from an infected person depends, for example, on how many virus particles they excrete. According to a new study, the amounts of virus that infected people emit when speaking or haunting, among other things, are higher for alpha, delta and omicron than was the case with the wild type of the coronavirus. In the event of an infection, vaccinated people also release viruses with their breathing air – frequent coughing can increase the release of the fine aerosols, especially with the omicron variant.
Between mid-2020 and early 2022, researchers from the University of Maryland examined a total of 93 subjects during their active Covid-19 infection. The participants had to fill out a questionnaire about their symptoms and vaccination status. The subjects’ infections were triggered by the variants alpha, delta or omicron. All participants with Delta and Omikron had already been vaccinated twice at the time of their corona disease.
Covid-19: Virus excretions higher in delta, alpha and omicron than in wild type
The scientists let the corona infected sing and scream in a cone-shaped apparatus – for half an hour. During this period of time, the subjects also had to sneeze and cough. A connected machine called “Health II” collected the particles. The machine separates the droplets from the fine aerosols, which have a diameter of 5 microns or less. These fine aerosols can also escape from a surgical mask.
Even if the researchers observed only a few subjects, they were able to determine that the virus shedding was higher in infections triggered by alpha, delta or omicron than in the wild type at the beginning of the pandemic.
“This research has shown that all three of these variants that won the infection race exit the body more efficiently when people speak or scream than the earliest strains of the coronavirus,” said John Volckens, a public health engineer at the state of Colorado University of Fort Collins, across from Nature. He was not involved in the study.
Amount of virus in subjects varies
The scientists could not prove any difference between the Delta, Omicron and Alpha variants. However, all subjects infected with the delta or omicron variant were already vaccinated. The researchers therefore do not know whether unvaccinated people who contract one of the two variants release higher amounts of the virus.
The scientists emphasize that the amount of exhaled virus varied greatly among the subjects – ranging from undetectable amounts to “superspreaders”. One subject coughed nearly 70 times during the study. He had released the largest amount of fine aerosols. It was 1000 times higher than the maximum values found for alpha and delta variants.
Study co-author Kristen Coleman, who is at the University of Maryland, told Nature of the study’s findings: “People should push governments to invest in improving indoor air quality by improving ventilation and filtration systems “.
Development of new variants
The researchers noticed another aspect: the amount of virus exhaled by Sars-CoV-2 infected people was lower than with influenza. This suggests that new variants could evolve that carry even more viruses.
One point of criticism of the study: The researchers made the subjects sing, scream, but also cough and sneeze. This means that the samples cannot be assigned to an airway. The study was published as a preprint, so it has not yet been evaluated by experts.
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Source: Stern
