On Jan. 6, America watched in horror as insurrectionists attacked the Capitol. In real time, we followed the livestreamed video and images of angry mobs ransacking the building while lawmakers barricaded themselves in their offices and evacuated chambers in escape hoods. For a few hours, I was so chilled by the national crisis unfolding that I forgot it was all happening against the backdrop of a raging pandemic. It’d be hard to design a more optimal superspreader event than the insurrection: People were forced into enclosed, indoor spaces together, often without masks, with lots of yelling and heavy breathing to transmit respiratory droplets.
In the two weeks since, at least eight members of Congress have tested positive for COVID-19. Reps. Adriano Espaillat, Bonnie Watson Coleman, Pramila Jayapal, Lou Correa, and Brad Schneider all had been previously vaccinated. (The offices of Reps. Michelle Steel, Jake LaTurner, and Chuck Fleischmann did not return my requests for comment.) It’s a situation likely to repeat itself in the American public as more people receive vaccines: What happens if partially vaccinated individuals are exposed to COVID?
It depends on many factors, but among the important is the timing of your vaccination. Three of the COVID-positive members of Congress—Jayapal, Watson Coleman, and Schneider—received their first vaccine dose Jan. 4. In a statement announcing her positive result, Watson Coleman explicitly states that “she believes she was exposed during protective isolation in the U.S. Capitol building as a result of insurrectionist riots,” and Schneider’s and Jayapal’s statements include strongly worded condemnations of their colleagues who refused to wear masks. If they were indeed exposed to the coronavirus during the Capitol insurrection, that means there was, at most, 48 hours between their vaccination and their exposure.
After just two days, the Pfizer and Moderna COVID vaccines—the ones currently available in the U.S.—are unlikely to provide much protection. To understand why, let’s go back to the basics: The vaccine essentially gives instructions to the body’s immune system to make a part of the spike protein, which is what gives the coronavirus those blobs you’ve likely seen in renderings of the virus. The spike protein on its own is harmless, and by making it, your body learns to recognize it and mount an immune response to it by creating antibodies. Basically, it gives your body a chance to practice so you’re ready for the real thing. “Usually, this takes a little while,” says Akiko Iwasaki, a professor of immunology at Yale University. “It takes a couple weeks for the antibodies to fully develop.” So, after just two days, “there’s no way you can develop antibody responses—so it’s not surprising these people got infected.”
Lou Correa, another representative who tested positive, says he received the first dose of the vaccine on Dec. 19, more than two weeks before the Capitol insurrection. In theory, that first shot provides some protection to people; data from clinical trials collected between participants’ first and second shots showed around a 92 percent efficacy, says Iwasaki, compared with 95 percent efficacy after both doses are administered.
As you have likely heard, the COVID-19 vaccines are given in two doses—and there’s good reason for that. If the first dose is practice, the second dose is a dress rehearsal. It helps hone your body’s response and improve its ability to find and destroy the virus’s spike protein. After the second dose, there’s still some lag time as your body fine-tunes its immune response. At least one member of Congress—Adriano Espaillat—received both vaccine doses and still tested positive for COVID-19, though it seems he received the second dose the week of the Capitol insurrection. “There are a lot of questions around that gray zone between the doses of vaccine, or in that time period after the second one, where you’re still considered susceptible,” says Benjamin Singer, an assistant professor of medicine at Northwestern University Feinberg School of Medicine.
Another thing to consider in these cases of COVID-positive members of Congress: whether they have experienced symptoms. As we’ve seen throughout the pandemic, lots of asymptomatic people test positive for the virus. Iwasaki points out that in vaccine clinical trials, vaccine efficacy is determined based on symptomatic infection, not whether they tested positive for the virus. “If a person was asymptomatic, that would’ve been considered protected [from the virus],” says Iwasaki. Espaillat, Correa, and Schneider have reported experiencing no symptoms; if they had been in a vaccine clinical trial, their vaccination would have been considered effective. After all, there’s a difference between carrying the virus—which is what testing determines—and infection. The main priority of a vaccine is to prevent infection in an individual, and trial data has shown current vaccines are very effective at that. What’s more, says Singer, is that even if you do develop an infection post-vaccination, current evidence shows it’s likely to be mild. “If you look at the thousands of people who participated in trials, there were essentially no cases of severe illness,” he says.
So if some vaccinated members of Congress are testing positive but not coming down with illness, what does that mean about their ability to spread the virus? “It remains an open question of how effectively people who are immunized via the vaccine can spread infection,” says Singer. “We know that people who acquired asymptomatic infections before the vaccine was available had levels of virus in their nose that are associated with the ability to easily transmit the virus,” but it’s not yet clear how vaccination might affect viral load and transmission.
Currently, the chain of infection within these representatives is unclear; LaTurner tested positive the day of the Capitol insurrection, meaning he was almost definitely exposed before the event, and in a statement, Fleischmann said he believes he was infected via Rep. Gus Bilirakis, at the residence they share in D.C. Though several members of Congress believe they were infected while sheltering in place at the Capitol, it’s possible they were exposed in the days before. Either way, each representative has committed to quarantining, which will hopefully break the chain of infections.
Even if there are still infected representatives in the mix, wearing masks could help prevent further spread, or at least decrease the severity of any infections. “If you wear a mask, the amount of virus you get infected with is lower,” says Singer. President Joe Biden’s new mask mandate on all federal property might help halt any further cases among lawmakers, if it’s enforced.
These representatives have been unfortunate examples of what can happen if you’re exposed to the virus shortly after vaccination. As more people get vaccinated, it’s important to remember that a vaccine—especially a single dose—does not immediately confer immunity. While that first shot may offer a moment of relief and new hope that we may someday travel maskless and hug friends again, those activities don’t magically become safe post-vaccination, and jumping into them could still result in illness or exposing others to the virus.