COVID-19 is an extremely communicable disease, but evidence shows that small indoor gatherings and households are where the new coronavirus spreads the fastest.
For almost a year, public health officials around the world have been confronted with how to reduce the spread of COVID-19. Sometimes travel has been restricted, schools and gyms have closed, and some cities, such as San Francisco, are closed. But despite these restrictions, the number of COVID-19 infections and deaths continues to reach records.
“I think we want to be careful about blaming a certain environment and the scapegoat on a certain framework for generating transmission,” said Dr. John Brownstein, an ABC News contributor, epidemiologist and chief innovation officer at Boston Children’s Hospital.
However, there are some settings in which COVID-19 spreads more easily. In New York, for example, follow-up has shown that 70% of new cases come from small assemblies and households.
“Informal gatherings could have played even the biggest role,” said Brownstein, “because they’re harder to police, harder to implement, and people are probably more cowardly when it comes to wearing masks.” and social distancing ”.
When people gather in small groups with friends and family, they are more likely to lower their guard, not wear masks and stay together indoors for longer periods of time, which makes it easier to transmit the virus.
In a recent study at the University of Mississippi Medical Center, researchers found that for children and teens who tested positive for COVID-19, small social gatherings – not school – were the most likely places they were exposed to the virus. .
Children who tested positive in the study were more likely to have attended social gatherings outside their homes, had play dates, or had visitors at home where no masks and social distance were taken.
At the beginning of the pandemic, after the initial blockades were eased and cases began to escalate, follow-up of contacts also linked the spread of the virus to restaurants and bars.
In a study published by the Centers for Disease Control and Prevention, people who were finally tested positive for COVID-19 were twice as likely to have eaten at a restaurant in the past two weeks compared to participants who did not. tested positive for the virus.
“The obvious challenge is losing control, wearing a mask,” said Dr. Joseph Allen, an assistant professor of exposure assessment science at Harvard TH Chan School of Public Health. “Since you have a restaurant with a lot of people talking loudly [with] it masks, which leads to higher rates of respiratory aerosol emissions and, depending on how the ventilation system works in the restaurant, determines how many infectious aerosols people breathe. “
Like small gatherings at home, people in restaurants often eat with people who are not in the immediate household and do not wear masks and are in a confined, poorly ventilated space.
“Gymnasiums have generally done a good job of adhering to protocols,” Brownstein said. “We don’t see a lot of super-popular gym-related events … because the protocols they had to implement in terms of social distancing, wearing and ventilating masks were generally pretty good.”
Schools are another setting in which many people are usually in a closed setting. Educational institutions have faced decisions regarding the conduct of in-person instruction versus class vs. distance learning to reduce transmission.
But Brownstein said schools were generally safe. “Of course there are aberrant values,” he added, “but we have seen good evidence that schools have spent time developing a protocol in which social distancing and wearing masks have done a relatively good job.”
There is also a lot of guidance regarding ventilation in schools, which makes the environment safer, Allen said.
Finally, when it comes to what drives high transmission rates in both homes and restaurants, it is “the common element of the basic factors,” Allen said. “Indoor time, no masks, low ventilation or no air.”
For weeks, experts have warned of the rise of new infections that would come with the Thanksgiving trip. We see that now. The imminent increase in travel and small indoor gatherings during the longer holiday week between Christmas and New Year could not come at a worse time, experts warn. However, certain measures can help.
“There’s no silver bullet when it comes to interventions. It’s kind of a stratified approach,” Brownstein said. “Social distancing and wearing a mask … indoor ventilation, assembly limitations … If people follow these general public health guidelines in a broad sense, they have really managed to drive the transmission down.”
Adjoa Smalls-Mantey, MD, D.Phil., Is trained in immunology and is a psychiatrist in New York City. She is also a contributor to the ABC News Medical Unit.