The classic American Thanksgiving has always carried some risk: driving to Grandma’s house, engaging in political conversations with family members, eating undercooked turkey. But in the COVID-19 era, people have also had to face serious concerns about gathering during a global pandemic.
As the country’s second COVID-19 Thanksgiving approaches, experts say the landscape of risk has changed. New variants have emerged, and tens of thousands of new infections are still occurring every day in the United States. Vaccines are available for everyone age 5 and older, but only 59 percent of people in the U.S. are currently fully vaccinated, and some populations remain at risk due to underlying conditions or compromised immune systems.
Data also suggest that bringing people together in groups does indeed raise the chances of passing along the SARS-CoV-2 virus. In the United States last winter, Thanksgiving and Christmas coincided with a COVID-19 wave, says Joshua Weitz, the founding director of the Quantitative Biosciences Ph.D. program at Georgia Tech in Atlanta, who currently has an appointment at the Institute of Biology at the École Normale Supérieure in Paris. Case rates varied by state, but the data show an accompanying nationwide peak in fatalities from about three weeks after Thanksgiving until February.
It’s impossible to know if upward trends after Thanksgiving happened because of people sitting around dinner tables, or if the real culprit was traveling across state lines, the change in weather that happens at the end of November, or something else, says Anupam Jena, an economist and physician at Harvard Medical School in Boston. (Find out why colder weather can make respiratory diseases like COVID-19 worse.)
Still, experts say that people can mitigate their risk this year in a variety of ways while enjoying the holiday. Among the possible steps to take: vaccination, rapid testing, checking local caseloads, and strategic ventilation.
“At this point of the pandemic, there's really no such thing as a zero-risk activity, and that should not be our goal,” says Leana Wen, an emergency physician and public health professor at George Washington University in Washington, D.C. “We need to figure out how we can live with COVID-19 in a way that allows us to enjoy the activities that we most value while trying to reduce risk as much as is reasonable.”
The birthday party experiment
In addition to last year’s winter surge, other lines of evidence back up the notion that small gatherings can increase the odds of spreading COVID-19. With the approach of his daughter’s December birthday last year, Jena considered having an in-person party for her. The family ultimately went with a magic show over Zoom, but the urge to invite friends over got him thinking that birthdays might provide an opportunity to study the role that small parties may play in the pandemic.
Using healthcare records that included birthdays from 2.9 million households around the United States, he and colleagues found that the number of COVID-19 diagnoses in a household were 31 percent higher in the week after someone in the home had a birthday. The researchers couldn’t tell how many of those birthdays involved parties. But the correlation over random dates throughout the year suggests that plenty of them did—and that the parties spread the virus.
In a related study of college students during the March Madness basketball tournament in the spring of 2021, Ashley O’Donoghue at Beth Israel Deaconess Medical Center in Boston analyzed numbers of newly reported cases in the weeks before and after a school’s team played in the tournament. The results showed rising case rates about eight days after games held in the counties of participating schools, suggesting that the virus spread when students got together to watch their teams play.
These kinds of parties tend to be places were people let their guard down, Jena says, which is something people have to consider when calculating their personal risk of catching and spreading the virus.
“Of course, people know that the virus gets transmitted by person-to-person contact,” he says. “But what we never knew was: what is the actual risk? If I go into a household and celebrate a birthday party, what’s the likelihood that I'm going to have COVID-19 in two weeks?”
Gauging Thanksgiving risk
Calculating your risk also depends on COVID-19 rates in your area, and some researchers are working on ways to help people visualize what that might look like for them.
At the beginning of the pandemic, when recommendations kept changing for limits on group sizes, Georgia Tech’s Weitz created a graph to illustrate how the number of people in a gathering would affect the likelihood that somebody in the group would be infected. After the graph went viral on Twitter, he kept hearing from people who wanted more localized risk assessments.
In July 2020 he and his colleagues launched an interactive website that allows users to calculate the chances that at least one person will have COVID-19 at an event, based on the number of people there and illness rates in your county. The site automatically pulls in data from the Centers for Disease Control and Prevention and other sources twice a day.
Around Thanksgiving last year, the researchers added smaller group sizes. Weitz says people can now use the tool to assess their chances of potentially getting exposed at family gatherings, depending on where guests are coming from or where they’re going. People can reduce the chances that one case will become many by changing their behaviors, he adds, like social distancing, meeting outdoors, and wearing masks.
“What we hope to do is to try to communicate to people very rapidly and visually that, hey, there's still a chance that someone in that group may be affected,” he says. “Therefore, let me take the steps to take precautions.”
Gearing up for a gathering
Regardless of where you are or where you’re going, one of the best precautions people can take is getting vaccinated, experts say, and that includes getting booster shots for anyone who is eligible. Even as breakthrough infections grow, unvaccinated people remain at higher risk of infection, hospitalization, and death, Wen says. They are also more likely to transmit the virus, including the Delta variant, according to a large study posted online in September that has not yet been peer reviewed.
For people who are not yet vaccinated, it’s too late to get all the benefits of immunization by Thanksgiving. People are considered partially vaccinated two weeks after their first shot and fully vaccinated two weeks after the second dose of a two-dose series, according to the CDC.
But data suggest that immunity builds over time, so “it is better to get vaccinated now if someone hasn't already,” Wen says, “especially as COVID cases are rising across the country.”
A study in Qatar published in October 2021 found a noticeable uptick in effectiveness beginning three weeks after the first shot. In Scotland, researchers found substantial protection for weeks after the first shot. Some experts say the first dose can start helping even sooner, especially for kids. Boosters can help after a week, data show.
A gathering of only vaccinated people is going to be lower risk then bringing unvaccinated people into the mix, Wen says, though behavior also matters. Even vaccinated people who spend time in large groups without masks will be more likely to bring the virus to a gathering.
Underlying medical risks matter, too, Wen adds. You might choose to gather with a group of healthy vaccinated people even if community rates are high. But you might want to take more precautions if someone in your family is immunocompromised, or if you have young children who haven’t been able to get vaccinated. Young children who have been able to get their first shots in the last few weeks won’t be fully vaccinated until after Thanksgiving.
Once people do get together, being outside remains safer than being indoors, studies show. If you are inside, opening windows and improving ventilation can reduce transmission.
Testing can also be a useful risk mitigation strategy, and rapid tests could be particularly useful this year, says Brooke Nichols, an infectious disease medical modeler at the Boston University School of Public Health. In the U.S. rapid tests are available over the counter at drugstores, which also offer appointments and sometimes allow walk-ins, though supplies have been limited and finding them can require searching around. Some community testing sites and clinics also have them.
When it comes to Thanksgiving, rapid testing the morning of the event or throughout a visit could be a great way to catch cases before they spread, Nichols says, as long as people isolate after getting a positive result. Besides superspreader events, households are where a lot of transmission happens, studies show.
“Testing before your Thanksgiving dinner or before you go for Thanksgiving could have a huge impact if everyone actually did it,” Nichols says. “If it's accessible and you can afford it and if you really want to reduce the risk of transmission on Thanksgiving, it's essential.”
Each precautionary measure is a layer of protection that can be combined to make Thanksgiving as safe as possible. No single layer is perfect, including vaccines. Wen suggests looking at case rates every day like a weather report and thinking of vaccines like raincoats.
“If you are in a drizzle, it will protect you very well and chances are you're not going to get wet,” she says. “But if you are in a thunderstorm, and if you are in multiple thunderstorms all the time, at some point you're going to get wet.”