Amount of Virus-Shedding by a COVID Patient Depends Upon the Variant: Study

The infected people can shed viruses into the air while talking, singing, shouting, sneezing or coughing. In the case of COVID-19, the shedding of the virus into the air has been a great concern. The viral particles floating in the air can make contact with other people and infect them. But, the question is, how much virus can an infected person shed? Well, new research has reported some interesting facts regarding this.

The new research has been published in the preprint server medRXiv. This claims that people infected with more contagious variants of the coronavirus—alpha, delta and omicron- can spew more viruses than those infected with other variants. Moreover, it is also known that people who get infected even after vaccination or after the booster dose can still shed viruses into the air. The findings also hint at improving indoor air quality through ventilation or filtration.

Kristen Coleman, a researcher of emerging infectious diseases at the University of Maryland, the study's co-author, recruited 93 participants between mid-2020 and early 2022. These participants were infected with SARS-CoV-2, the coronavirus that causes COVID-19. The participants were infected with different strains or variants of the virus, namely the alpha variant that emerged in late 2020, along with the delta and omicron variants. All the participants in the study that were infected with the delta and omicron variants were fully vaccinated before contracting the virus.

The participants were faced with cone-shaped apparatus, and they were asked to sing, shout, cough and sneeze for 30 minutes. In the meantime, another attached machine collected the viral particles they exhaled. This device, named Gesundheit-II, could separate the aerosol particles of size less than 5 micrometres in diameter. These tiny aerosols can linger in the air for a long time and can leak through even surgical masks.

The researchers found that the participants infected with alpha, delta and omicron variants could emit more virus RNA than those infected with other variants. Importantly, the delta and omicron infected participants exhaled fine aerosol particles that contained five times more virus than their larger aerosols.

The researchers also highlighted the variation amongst the individuals, especially in the amounts of virus they exhaled. They found that the exhaled amount of virus ranged from an almost non-detectable level to that associated with a superspreader. They found that omicron-infected people could shed 1000 times more viral RNA than those infected with either delta or alpha variants.

However, there can be other factors involved as well, the researchers pointed out. The differential spreading could be related to the biology of a patient, such as age. Or, it could be attributable to behaviour as well. They found that the superspreaders in their study coughed more frequently than others.

The team also observed that people infected with SARS-CoV-2 exhaled much lower RNA of the virus than those infected with influenza. Notably, influenza is also an air-borne disease.

The team also took cells in the laboratory and exposed them to aerosol samples. They found four samples from a delta or omicron infected participant could infect the laboratory cells. This is indicative of the fact that exhaled viral RNA can spread the disease.