COVID-19 is a highly communicable disease, but evidence shows that small indoor meetings and residences are where the new coronavirus is spreading most rapidly.
For nearly a year, public health officials around the world have struggled to reduce the spread of COVID-19. Sometimes travel is restricted, schools and gyms close and some cities, like San Francisco, are closed. But despite these restrictions, the number of COVID-19 infections and deaths continues to reach record levels.
“I think we want to be careful not to blame a specific environment and use the scapegoat to generate the transmission,” said Dr. John Brownstein, ABC News contributor, epidemiologist and director of innovation at Boston Children’s Hospital.
However, there are some configurations in which COVID-19 is more easily distributed. In New York, for example, contact tracking showed that 70% of new cases come from small meetings and families.
“Informal meetings may have played an even bigger role,” said Brownstein, “because they are more difficult to police, they are more difficult to enforce and people are probably more relaxed when it comes to recommendations for wearing masks and social distance.”
When people gather in small groups with friends and family, they are more likely to let their guard down, not wear masks and spend more time together indoors, which facilitates the transmission of the virus.
In a recent study by the University of Mississippi Medical Center, researchers found that for children and teenagers who tested positive for COVID-19, it was at small social gatherings – not at school – the most likely place where they were exposed to the virus.
Children with a positive result in the study were more likely to attend social gatherings outside the home, have meetings or receive visits to their home where the wearing of a mask and precautions of social distance were not taken.
In the beginning of the pandemic, after the initial blocks were eased and the cases started to increase, the contact tracking 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 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 test positive for the virus.
“The obvious challenge is that you lose important control, wearing the mask,” said Dr. Joseph Allen, assistant professor of exposure assessment science at the Harvard School of Public Health TH Chan. “Since you have a restaurant with a lot of people talking loudly [with] without the masks, this leads to higher emission rates of respiratory aerosols and, depending on how the ventilation system is working in the restaurant, determines how many infectious aerosols people are breathing. “
Similar to small meetings at home, people in restaurants often eat with people who are not in their immediate home and do not wear masks, and are in a confined space with little ventilation.
“Academies have generally done a good job of adhering to protocols,” said Brownstein. “We don’t see many over-dispersed events related to gyms … because the protocols they have had to implement regarding social distance and the use of masks and ventilation have generally been very good.”
Schools are another environment where normally many people are in a closed environment. Educational institutions have struggled with decisions about whether to take face-to-face classes in the classroom or remote learning to reduce transmission.
But Brownstein said that schools are generally safe. “Of course, there are discrepancies,” he added, “but we have seen good evidence that schools have taken the time to develop a protocol where social detachment and wearing masks have done a relatively good job.”
There are also many guidelines regarding ventilation in schools, which makes the environment safer, said Allen.
Ultimately, when it comes to what drives high transmission rates in homes and restaurants, it’s “the similarity of the underlying factors,” said Allen. “Time indoors, without masks, little or no ventilation.”
For weeks, experts warned of the rise in new infections that would come with Thanksgiving trips. We are seeing this now. The imminent increase in travel and small internal meetings during the long holiday week between Christmas and New Year could not come at a worse time, experts warn. However, certain measures can help.
“There is no magic solution when it comes to interventions. It’s kind of a layered approach,” said Brownstein. “Social detachment and wearing a mask … internal ventilation, meeting limitations … If people are adhering to these general public health guidelines in a broad sense, they have been very successful in reducing transmission.”
Adjoa Smalls-Mantey, MD, D.Phil., Majored in immunology and is a psychiatrist in New York City. She is also a contributor to the ABC News Medical Unit.