If you enthusiastically vaxxed up partly out of a desire to be social again, you wouldn’t be alone—catching up friends in real life is one of the perks of COVID-19 vaccination.

But vaccination rates in the US have fallen short of expectations, and now the highly infectious Delta variant is fueling an increase in outbreaks, particularly in under-vaccinated areas of the country. The Delta variant currently accounts for 83% of COVID cases sequenced in the US, Rochelle Walensky, MD, director the U.S. Centers for Disease Control and Prevention (CDC), testified at a Senate committee hearing on Tuesday.

What does the current situation mean for Sunday brunches, backyard barbeques, and other activities if you’re vaccinated but you friends or family members are not? Is it still OK to hang out?

Here’s what public health officials and experts in infectious disease and emergency medicine are saying about what’s safe and what precautions you may want to take.

Aren’t most people vaccinated by now?

Don’t assume everyone in your life has had their shots. By the CDC’s count, 161.5 million Americans have been “fully vaccinated.” The means they’ve either had the single-dose Johnson & Johnson/Janssen vaccine or a second jab of the two-dose Pfizer or Moderna vaccine and at least two weeks have passed since they’ve completed the vaccination, which gives their immune systems time to mount a response.

Sounds like a lot of people, and it is. Still, only less than half (49%) of the US population—or slightly more than half (57%) if you exclude kids under age 12 who aren’t yet eligible for the vaccine—are fully protected. Vaccination rates can also vary significantly from one county or state to another.

Bottom line: millions of people are still walking around unprotected and vulnerable, and that includes young children.

I’m vaccinated. Can I hang out with unvaccinated friends?

Ultimately, the answer may depend on your own health, the health of others around you, and your risk tolerance.

“If you’re fully vaccinated, most interactions are quite low-risk for you,” Paul A. Thottingal, MD, a Seattle-based physician and infectious disease leader with Kaiser Permanente, tells Health. “But you may want to know about other people’s vaccination status to help think through how you can make activities as low-risk as possible for everybody,” he says.

That may mean masking up if you’re spending time at an indoor venue, like a bar or restaurant, or meeting up outdoors instead. “Out in the open air, I think you’re OK,” says Dr. Thottingal.

Megan L. Ranney, MD, professor of emergency medicine at Brown University in Providence, Rhode Island, would err on the side of caution.

“In general, if I were to hang out with an unvaccinated friend, I would only do so outdoors or when masked,” she tells Health. Although the vaccines are “marvelously effective,” she wouldn’t want to risk acquiring a breakthrough infection, much less (hypothetically speaking) transmit the infection to an unvaccinated child or parent.

William Schaffner, MD, professor of infectious diseases at Vanderbilt University Medical Center in Nashville, recalls “very complicated discussions” he’s had with families who wish to have small visits with frail family members, often older persons. The family, for example, may have been quite careful, though not rigidly so, and the children are younger than 12, so they haven’t been vaccinated. “And I say get together with the family and figure out with the ground rules are that everyone’s comfortable with before the visit.”

He also suggests teaching kids how to keep grandma and grandpa safe by keeping masks on during the visit and hugging their grandparents around the waist—once when you arrive and again when you depart—then backing off.

If you’re having friends over who have with unvaccinated kids, Dr. Thottingal suggests that everyone in the house mask up. “It’s easier to the support the kids if everybody’s wearing a mask without singling them out,” he says.

In “hot spots” where the virus is circulating, it may make sense to take extra precautions.

“People assess their own risk tolerance,” Dr. Schaffner reasons. “If you’re in Vermont, you’re in a very difference circumstance than if you were in my state of Tennessee.” (Seventy-seven percent of Vermont’s 18-and-older population is fully vaccinated, versus close to 48% in Tennessee, per the New York Times.)

In Los Angeles County, an indoor mask mandate has been reinstated after a recent surge in cases and hospitalizations. “Masking indoors must again become a normal practice by all, regardless of vaccination status, so that we can stop the trends and level of transmission we are currently seeing,” LA County Health Officer Muntu Davis, MD, said in a statement.

And remember, even if you’ve had your jabs, you and your unvaccinated friends will have to mask up if you’re using public transportation or passing through transportation hubs, such as airports and train stations.

One more suggestion: If you’re meeting up with have a friend who’s unvaccinated, Mirella Salvatore, MD, an infectious disease specialist assistant professor of medicine at Weill Cornell Medicine in New York City, suggests using the opportunity to talk about vaccination. “Try to understand why they don’t want to get vaccinated, or maybe you can share your experience with the vaccine,” she says.

“We have to think globally—not only for ourselves,” says Dr. Salvatore, but for the community at large.

Do I need to wear a mask to hang out with unvaccinated friends if I’m vaccinated?
CDC continues to assure fully vaccinated folks that it’s OK (with a few notable exceptions) to resume pre-pandemic activities without masking up or physically distancing. That’s because vaccines have been shown to be highly effective against severe disease due to the virus that causes COVID-19, including variants.

“At their best, the vaccines are 95% effective in keeping us out of the hospital,” Dr. Schaffner tells Health. But vaccination also reduces the risk of becoming infection and, in turn, substantially reduces the risk of transmitting the disease, he says.

The COVID-19 vaccine trials were designed to assess the impact of vaccines on keeping people out of the hospital and other severe outcomes. “That we got a reduction in infection and consequent transmission was kind of a bonus,” says Dr. Schaffner.

All that’s to say the vaccines go a long way toward in keeping vaccinated people protected. “But they’re not perfect,” he allows. And that’s where other mitigation measures, like masking, may come into play.

I’m vaccinated but immune compromised—now what?

If you’ve been vaccinated but your immune system is weak because of a medical condition or medications you’re taking, CDC recommends that you take additional precautions, such as wearing a mask in indoor public places, unless advised otherwise by your doctor. While the COVID-19 vaccines reduce the risk of getting and spreading the virus, people who are immune compromised may not be protected, even if they are fully vaccinated, CDC notes.

If you have reason to believe your immune system is compromised, you shouldn’t forgo masks because you don’t want to expose yourself to any risks, says Dr. Salvatore.

“Being vaccinated is a great thing but doesn’t make you Superman,” she says. “Mostly with these variants that are more transmissible, you want to be extra cautious if you think that you have any disease that you might not mount a perfectly good immune response.”

Dr. Schaffner offers similar advice. If you think the vaccine may not be providing optimal protection, “sure, wear a mask, and to the degree that you feel comfortable, do social distancing,” he says.