Viruses in exhaled air infect more people – especially if they are talking or singing

There are more viruses in exhaled air when symptoms appear and when speaking or singing. This is evidenced by a new study from Lund University in which researchers measured the amount of virus in people with covid-19. COVID-19 has also infected more household contacts with viruses in exhaled air during home quarantine.

At the start of the COVID-19 pandemic, aerosol researchers in Lund showed that singing—especially loud, rich singing—diffuses many aerosol particles and large droplets into the surrounding air. This suggests that singing can increase the risk of spreading the coronavirus, for example. However, in that study, they did not specifically look for the coronavirus, even though few samples were taken from patients.

The search has now This was followed up by a new study in which researchers visited confirmed cases of coronavirus in a portable laboratory mounted in a truck. There, patients were allowed to breathe, talk and sing in a kind of funnel connected to measuring equipment, where it was possible to analyze the amount of coronavirus in the exhaled air. The results have now been published in the scientific journal Clinical Infectious Diseases.

– 19 of the 38 people we tested – that’s 50 percent – had positive breath samples for coronavirus, and the percentage was higher at the onset of symptoms. For those who had symptoms for five to six days, we couldn’t find any viral particles in the exhaled air, says Malin Alsved, an aerosol technology researcher at LTH.

who have been examined We first had to breathe in the funnel for 10 minutes, then speak freely for the same length of time, and finish singing for 10 minutes. The results showed that more people spread the virus in exhaled air when they spoke and sang compared to when they just breathed.

The study also followed how the infection spread in the participants’ homes. Through this, it became possible for the first time to show a direct link between viruses in airborne particles (aerosols) and transmission.

– There were twice the number of infected in homes where the first infected person had measurable amounts of virus in exhaled air, compared to households where the first infected person, despite confirmed Covid-19, did not exhale measurable amounts of virus in the air, as Malin Alsafid says.

Different people seem to spread different amounts of infection through the air, indicating that different people get infected in different amounts. The odds of finding viruses in aerosol samples were greater at the onset of symptoms and decreased with each passing day.

– Malin Alsavid says that those who spread the most caught the Covid virus in exhaled aerosol particles more than 100 times than those who were least spread.

Although half of the patients Breath samples are virus positive, it is not certain that all samples are infected with a contagious virus. However, given that most of them have recently contracted the disease and the fact that a positive air test also entails an increased risk of infection of household contacts, this suggests that these people can already be infected by airborne viruses. Experiments are currently underway to see if cells in the laboratory can be infected with viruses from these air samples, to prove that they contain live infectious viruses, but the results are not yet clear.

With this research, we hope to be able to determine how infectious a person with the virus is, says Malin Alsved.

Study link: https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciac202/6546685

The project was implemented in collaboration between Human Engineering and Aerosol Technology at Lund University of Technology, Infectious Medicine and Nursing Health at Skene University Hospital and Clinical Virology at Lund University School of Medicine. The funders are Formas, Afa Försäkring and the Royal Physiographic Society.

For more information please contact:
Malin Alsved, Researcher in Aerosol Technology at LTH, Lund University, 046-222 39 32, 0702-44 48 34, [email protected]

Lund University was founded in 1666. There are 40,000 students and over 8,000 employees in Lund, Helsingborg and Malmö. We unite in our quest to understand, explain and improve our world and human conditions. Lund University has been repeatedly ranked as one of the 100 leading universities in the world.