About a year into the global pandemic, as the worldwide death toll exceeds a dizzying 2.5 million—more than half a million in the United States alone—hope has arrived in the form of multiple vaccines created in record time that have shown impressive success in preventing COVID-19.
“What all the vaccines have been is very highly protective against severe disease, hospitalization, and death,” says William Moss, executive director of the International Vaccine Access Center at Johns Hopkins Bloomberg School of Public Health. That, he says, is the most important success story of COVID-19 vaccines and will help bring this brutal pandemic under control.
With the number of vaccinated individuals growing daily, many wonder: What previously risky activities, such as meeting up indoors with friends or going out shopping without a mask on, are now safer with a vaccine?
On March 8, the U.S. Centers for Disease Control and Prevention released their interim recommendations for people who have been fully vaccinated. The new guidance eases restrictions in select circumstances, with the agency acknowledging that doing so may encourage more people to get vaccinated. However, the CDC cautions that research is still being done to test how long protection lasts and how much protection the available vaccines offer against emerging variants, so vaccinated people will still need to be mindful of the risks of transmitting the virus to others.
This is what the CDC and other experts say about how to calculate the risks of some common activities after you’ve been vaccinated.
How long after being vaccinated does 'full' immunity kick in?
The two mRNA vaccines that are currently approved for use in the U.S., Moderna and Pfizer-BioNTech, involve two doses spaced three or four weeks apart to achieve the maximum level of protection from COVID-19. In clinical trials, these vaccines are each about 95 percent effective in preventing cases of COVID-19. The Johnson & Johnson viral-vector vaccine that is also authorized in the U.S. is a single-dose shot with an efficacy rate of 72 percent.
In its guidance, the CDC says people are considered fully vaccinated two weeks after they receive either the second dose of an mRNA vaccine or the single dose of the viral-vector vaccine.
At this point, it is unknown how long immunity will last after a person is fully vaccinated. The COVID-19 vaccine could become a yearly shot, similar to the flu shot; its benefits could last for a shorter time, or longer.
Can vaccinated people have no symptoms and still spread the virus to the unvaccinated?
This question is critical, but has not been rigorously studied yet. The data available so far indicate that vaccination significantly curbs infection in people who show no symptoms. In Moderna’s phase 3 clinical trial, a diagnostic test before the second dose of the vaccine showed 89.6 percent of asymptomatic and symptomatic cases were prevented by the first dose.
That result is “really encouraging,” says John Swartzberg, clinical professor emeritus at University of California Berkeley’s School of Public Health. “That's going to make me feel, as a responsible person, that I can more safely be around other people.”
How safe is it for vaccinated people to get together?
As part of its interim recommendations, the CDC says that people who are fully vaccinated can gather with small groups of other fully vaccinated people indoors without masks or social distancing. The agency also says that the fully vaccinated can meet with unvaccinated people from a single household who are at low risk for developing severe forms of the disease, no masks or distancing required.
Still, the decision for vaccinated people to gather involves mental “calculus,” says Swartzberg, which should take into account how likely anyone is to be exposed to the SARS-CoV-2 virus, vaccinated or not, because there is still a small chance even a vaccinated person could become infected or that they could infect an unvaccinated person.
As time goes on, when more people are vaccinated and the number of infected individuals continues to drop, Moss says a gathering among vaccinated people “will be a safe one” and continue to get safer.
“To be on the safe side,” says Cynthia Leifer, associate professor of immunology at Cornell University, “we should still practice distancing measures as much as we can in the shorter term until we get broader distribution of the vaccine.” She recommends people continue to follow the guidelines of avoiding large groups, wearing masks, and staying at least six feet apart.
There are also unknowns surrounding how effective the vaccines will be against new variants, including ones that haven’t been discovered yet.
“The more that COVID is circulating right now, the more potential there is for variants to arise,” Leifer says. “We can’t predict when a new variant might arise that is perhaps not covered by the vaccine.”
The Novavax vaccine, which is not yet approved for use, showed a sizable drop in efficacy—from 89.3 percent to 49.4 percent—against a variant that originated in South Africa but has since spread internationally. Pfizer and Moderna are still testing how well its vaccines work against a more contagious variant first discovered in the U.K.
Should vaccinated people still wear masks in public places?
Experts including the CDC agree that everyone should wear masks in public, at least for the time being. Beyond not knowing who is vaccinated and who isn’t, which could potentially lead to awkward and confusing situations, each person can have a different immune reaction to a vaccine.
“So, you immunize 100 people, they're all going to have varying levels of response to that vaccine; some may be not good enough to protect them,” Leifer says. There is really no way to know what kind of response your own body had to the vaccine, so wearing a mask adds an extra layer of protection. There is also still the open question of how much people who have had the vaccine will be able to transmit the virus.
The CDC recommendations also say that even fully vaccinated people should wear masks and maintain distance when visiting people who are at higher risk of severe COVID-19 and those who live in multiple households.
“I look at the vaccine as a big patch, but there are other patches we can have to protect ourselves," Swartzberg says. “The vaccine is probably the biggest one.” Another such patch is a mask, and he does not think anyone should stop using one in public.
Is it safe to travel after I am vaccinated?
For many, it has been months or years since they have been able to meet family and friends face to face, but getting the vaccine doesn’t automatically mean it is entirely safe to travel the world.
“I think it comes down to what people feel comfortable with, but they need to be aware that we can't at this time predict when new variants will arise, where they will arise, and whether you'll be protected,” Leifer says. “It's not like when you get the vaccine, you all of a sudden have a Captain America shield around you.”
Swartzberg says while he may soon feel safe socializing in small groups with other vaccinated individuals, air travel is a different story: “I'm not going to know who's in the airport, who's in the airplane ... so it's going to be much longer before I'm confident that there aren’t going to be a lot of unvaccinated people on that airplane or in that airport.”
How long will it be until enough people are vaccinated to go 'back to normal?'
The easygoing world of 2019 may now be a distant memory, but with the vaccine rollout underway, a cautious sense of normalcy—eating at a restaurant, going to school, karaoke night with friends—seems within grasp.
So far, over 300 million people have been vaccinated worldwide. In the United States, around 30.7 million people have been fully vaccinated. Estimates suggest 90 percent of the U.S. population will be at least partially vaccinated by September at the current pace; researchers say between 75 and 80 percent of the population will need to get vaccinated before the country reaches herd immunity.
On the road to herd immunity, there will be signs that normalcy may be returning. Swartzberg says he will feel better as the number of new cases decreases, lessening the chance of being exposed to the virus.
“The way I see this playing out is that it's going to be kind of a phase transition back to pre-pandemic times,” says Moss. The first step is to reduce cases, hospitalizations, and deaths through vaccination so thorough contact tracing can be implemented in an effective way. “Even though we talked about tracing, what happened was the case numbers were so high throughout the United States that it just overwhelmed that system,” he says.
Leifer is hopeful that the vaccine rollout can speed up with creative distribution and manufacturing plans. “My vision would be that we get there by the end of the summer, so that students can go back to school,” she says.
A vaccine isn’t a golden ticket, but it provides people a way to reduce their risk and get back to their loved ones sooner.
“I haven't hugged my grandchildren and children, going on 10 months now,” Swartzberger says, “At some point I really need to do that.”
Editor's note: This story has been updated to include interim recommendations from the CDC. It originally published on February 10, 2021.