In the United States, those vaccinated can congregate indoors, according to the CDC.

Fully vaccinated Americans can now congregate indoors, without masks and without distancing, as long as it is with other people who have been vaccinated, according to new direction from the Centers for Disease Control and Prevention.

The counseling, which comes as vaccinations continue to gain momentum in America, is a positive signal for those who have had a series of vaccines. But it shows that there’s a lot we still don’t know about how the virus behaves – and it leaves a lot of questions about who can do what and what is right.

Three things the new CDC guidelines say

• Indoor gatherings, without masks and without distance are acceptable, as long as individuals have been fully vaccinated for at least 2 weeks. The CDC says medium and large gatherings should always be avoided, although it doesn’t specify a number of people for a small gathering.

• In public, keep your mask on and continue to distance yourself from others. When you are in your community on the train or at the grocery store, you might run into people who have not yet been vaccinated.

• Vaccinated and unvaccinated people can come together, with limitations. If you’re vaccinated, the CDC says you can go inside unmasked with unvaccinated people from another household. There are important considerations to this, such as the health profiles of the unvaccinated people involved, discussed below.

Three things that remain unanswered

• If vaccinated people are still considered a risk of transmission. We know that vaccinated people are much less likely to be infected and much less likely to transmit the virus, but the CDC has yet to say what that means for people’s behavior. It is essential for those vaccinated to understand that interacting with other people who have not been vaccinated or infected carries “an indefinite and finite risk,” says Thomas Russo, professor of infectious diseases at the University of Buffalo. This risk of transmission can be reduced, but it is probably not zero.

• Can vaccines prevent the long-term effects of covid-19 – and what are they? All vaccines approved for emergency use in the United States have been shown to be very effective in preventing death, but we are still learning about the long-term effects of covid-19. Even people with relatively minor cases could still fight the symptoms for weeks or months. The safest bet, Russo says, is to do whatever you can to keep yourself from getting infected.

• What should be your personal risk tolerance. Although CDC guidelines state that unmasked indoor gatherings are acceptable between a vaccinated person and unvaccinated people in a household, there is a big caveat: if someone in the unvaccinated household is within a increased risk of severe covid-19 disease.

  Even if you read information about health conditions that increase risk, “there are still people who end up getting serious illness for reasons we’re not sure,” Russo says. “[The guidelines] count on the public to solve this problem. This risk calculation can be particularly tricky if you live with people who have been vaccinated but others who do not. Russo, who lives in a mixed household, says he takes a conservative approach and is as careful as he can get.

More of the same… for the time being

While these new guidelines may give some families the peace of mind of arranging much-needed visits with grandparents, little has changed today for the vast majority of the United States, especially for people of color. New York Times analysis found that blacks were under-immunized relative to their population in each of the 38 states that report race and ethnicity for immunizations. A gap also exists for Hispanics. And although the new CDC guidelines only apply to private activities – not large-scale public reopening – bioethicists have warned that using immunization status as a prerequisite for participation in the reopening could further reinforce existing racial inequalities.

“We have to do everything we can to make the immunization process fair and just,” says Russo, “and we’re still struggling.”

This story is part of the Pandemic technology project, supported by the Rockefeller Foundation.