In her article, Erin Bromage, a professor of biology at Dartmouth University in Massachusetts, tried to explain how infectious diseases spread. He assessed the risk of coronavirus infection in various situations, including weddings and birthdays. The professor concluded that the probability of getting a virus outside and taking the virus is relatively low.
As reported by Armenpress, the professor tried to answer many questions.
Where do people get sick?
Most people become infected at home. One of the members of the house is infected with the virus in the community, outside, and is brought home, where constant contact with other members of the household leads to infection.
But where do people get infected in the community? The biologist noted that he often hears that people are afraid of grocery stores, cycling, runners who do not wear a protective mask … Are these places a concern? According to the professor, not so much. he explained. In order to be infected, you need to be exposed to the contagious dose of the virus. Examination of infectious doses of other coronaviruses shows that only a small dose may be needed for infection. Some experts estimate that as few as 1000 SARS-CoV2 virus-infected particles are enough. “Please note that this has yet to be determined experimentally, but we can use that number to show how the infection can occur. Infection can be caused by 1000
infectious virus particles that you get in one breath or by rubbing (trampling) the eye once, or by 100 viral particles that penetrate every 10 breaths. Each of these situations can lead to the spread of infection, ”said the professor.
How long does it take for the virus to be released into the environment?
Bathrooms. Bathrooms (toilets) have many touch surfaces: door handles, faucets, etc. Thus, the risk of transmission in this environment can be high. We need to be more careful with public toilets as we learn more about risk.
The thousand. One cough releases about 3,000 drops, and the drops can travel up to 50 miles per hour. Many of the drops are large and fall quickly, but many remain in the air and can spread throughout the room in a matter of seconds.
Whispering. As a result of one sneeze, about 30,000 drops are released, the drops move up to 200 miles per hour. Most of the drops are small and spread over large areas (easily through the room).
Thus, if a person is infected, a single cough or sneeze can contain up to 200 million virus particles, all of which can spread to their environment.
Breathing. As a result of one exhalation, 50-5000 drops are released. Most of these droplets are slow and fall to the ground quickly.
Unlike sneezing and coughing, which release large amounts of viral particles, breathing droplets only contain low levels of the virus.
Talking increases the release of respiratory droplets by about 10 times – 200 virus particles per minute. Assuming that each virus is involved, a face-to-face conversation will take 5 minutes to obtain the required dose. Anyone who spends 10 minutes talking face to face is potentially infected. Thus, anyone who shares space with an infected person, such as at work, for a longer period of time, is potentially infected. That’s why it’s important for people with symptoms to stay home. The professor noted that sneezing and coughing cause so many viruses that they can infect people in an entire room.
What is the role of asymptomatic people in the spread of the virus?
The virus is not only spread through symptomatic people. At least 44% of infected people have no symptoms. The virus can be spread in the environment up to 5 days before the onset of symptoms.
Then, Erin Bromage presented an example of how 94 out of 216 employees on the same floor became infected a week after one infected person went to work. Moreover, 2 of them were asymptomatic. However, it was not possible to determine the mode of transmission of the infection, it could be the elevator button, the door handle, the water machine, etc. Three people working in the same building but on different floors were infected. Although there were contacts between the employees of different floors of the building, in the elevator and in the lobby, the outbreak was limited to only one floor.