After 16 months of caution, even fully vaccinated people are naturally worried about their risks of contracting COVID-19 in situations where it is unknown who has been vaccinated or not. As people start socializing more with their families in various indoor and outdoor settings, many are concerned about their risks when mingling with individuals who may not have received the COVID-19 vaccine.

According to The Boston Globe, Dr. Daniel Kuritzkes, a professor of infectious diseases at Harvard Medical School, says the risks of infection for a vaccinated individual who comes into close contact with an unvaccinated person is “very, very low.”

“They can’t be said to be zero, but they are very, very low,” he said. “Outdoors, the risk is probably zero.” Indoors, in a crowded room, with the potential for many unvaccinated people to be present, Kuritzkes advises continuing to wear a mask. The expert adds that his advice is pertinent only to those living in Massachusetts, where vaccination rates are high, and the number of COVID-19 cases are low.

“It’d be different if you decided to go to Texas or to some place where there’s a smaller number of people who are vaccinated and if they’re still having a significant number of cases,” he told the Globe. “Then, wearing a mask might be more important to be absolutely certain that you are protected.”

Some parents worry that even if they are vaccinated, they could infect their children who are not yet  eligible for the COVID-19 shot. Experts said that it is highly unlikely, and if children do become infected, they will not transmit the virus to others because vaccinated people carry an extremely low viral rate in their airways.

Children under the age of 12 should continue to wear face coverings in indoor settings and even outdoors if they are sitting in a crowd.

“In indoor settings, particularly, or crowded outdoor settings like a ballpark or an outdoor concert, where people are packed in tightly, they should continue to wear masks,” said Kuritzkes. “I don’t think they need to wear masks if they are going to be at a family gathering where people have been vaccinated.”

The expert warns that bringing kids to gatherings that include unvaccinated individuals increases their risk for COVID-19 infection, so he recommends that they wear masks.

Physical contact such a hugs, high-fives and handshakes are okay among vaccinated people, but not among those unvaccinated says Dr. Helen Boucher, an infectious disease expert at Tufts Medical Center. Boucher, the chief of geographic medicine and infectious diseases at Tufts, tells the Globe that “if only one person is vaccinated and the other person is not vaccinated, then the risk is higher. In my personal practices, if I’m coming in contact with people who are not vaccinated, I wouldn’t have close contact.”

Kuritzkes is more lenient. “Hugging relatives is probably minimal risk. I’d be a little more skeptical about handshaking just as a form of social greeting. But I think if you hug your relatives, and you’re vaccinated, that’s fine.”

And people who have received only their first dose of a two-dose vaccine, should continue to exercise caution.

Dr. Scott Gottlieb, the former commissioner of the Food and Drug Administration, said that people who have received their first COVID-19 shot should continue to wear masks and take necessary precautions to avoid infection from the virus. A person is not considered to be fully vaccinated until two weeks have passed after their final shot.

Speaking with CNBC, Gottlieb said his advice is especially important for older Americans who are at increased risk for complications from COVID-19.

“I think for an older individual who is vulnerable to the virus, certainly wait for a period of time after the second shot until you’re likely to have full protective immunity,” he said. “I don’t think people should feel completely secure after the first shot.”

Experts are optimistic that this summer can be as enjoyable as pre-pandemic days, especially for vaccinated adults who are not immunocompromised and do not have children.

“The infection numbers continue to decline, the vaccination numbers are going up,” Boucher told the Globe. “The weather is good and there’s lots of ways to get outside so I’m optimistic that it’s going to be a much better summer than last year.”