Can I still spread the coronavirus after I’m vaccinated?

It’s possible. Experts say the risk is low, but are still studying how well the shots blunt the spread of the virus.

The current vaccines are highly effective at preventing people from getting seriously sick with COVID-19.

But even if vaccinated people don’t get sick, they might still get infected without showing any symptoms. Experts think the vaccine would also curb the chances of those people spreading the virus.

“A vaccinated person controls the virus better, so the chances of transmitting will be greatly reduced,” said Dr. Robert Gallo a virus expert at the University of Maryland School of Medicine.

Among the evidence so far: Studies suggesting if people do get infected despite vaccination, they harbor less coronavirus in the nose than the unvaccinated. That makes it harder to spread.

Trying to settle the question, the U.S. is starting a study of college students willing to undergo daily nasal swab testing.

Given the uncertainty and the arrival of more contagious variants, experts say fully vaccinated people should continue to wear masks and social distance in public and when visiting with unvaccinated people at high risk for severe illness if infected.

“We still have to be cautious,” Gallo said. “The vaccine is essential. But it is not a cure-all that ends the epidemic tomorrow.”

Other factors can also affect the likelihood of a vaccinated person spreading the virus, including vaccination rates in the community and whether there’s an ongoing surge in cases locally.

“We want to think it’s all or none, but it’s very situation-specific,” said Dr. Laraine Lynn Washer, an infectious disease expert at the University of Michigan.

Are some COVID-19 vaccines more effective than others?

It’s hard to tell since they weren’t directly compared in studies. But experts say the vaccines are alike on what matters most: preventing hospitalizations and deaths.

“Luckily, all these vaccines look like they’re protecting us from severe disease,” said Dr. Monica Gandhi of the University of California, San Francisco, citing study results for five vaccines used around the world and a sixth that’s still in review.

And real-world evidence as millions of people receive the vaccines show they're all working very well.

Still, people might wonder if one is better than another since studies conducted before the vaccines were rolled out found varying levels of effectiveness. The problem is they don't offer apples-to-apples comparisons.

Consider the two-dose vaccines from Pfizer and Moderna, found to be about 95% effective at preventing illness. Studies for those shots counted a COVID-19 case whether it was mild, moderate or severe - and were conducted before worrisome mutated versions of the virus began circulating.

Then Johnson & Johnson tested a single-dose vaccine and didn't count mild illnesses. J&J’s shot was 66% protective against moderate to severe illness in a large international study. In just the U.S., where there's less spread of variants, it was 72% effective. More importantly, once the vaccine’s effect kicked in it prevented hospitalization and death.

AstraZeneca's two-dose vaccine used in many countries has faced questions about the exact degree of its effectiveness indicated by studies. But experts agree those shots, too, protect against the worst outcomes.

Around the world, hospitalizations are dropping in countries where vaccines have been rolling out including Israel, England and Scotland - regardless of which shots are given. And the U.S. government’s first look at real-world data among essential workers provided further evidence that the Pfizer and Moderna vaccines are highly protective - 90% - against infections whether there were symptoms or not.

What is a COVID-19 vaccine passport, and will I need one?

“Vaccine passports," or vaccine certificates, are documents that show you were vaccinated against COVID-19 or recently tested negative for the virus. They could help you get into places such as stadiums or even countries that are looking to reopen safely.

The certificates are still being developed, and how and whether they’ll be used could vary widely around the world. Experts say they should be free and available on paper, not just on apps, since not everyone has a smartphone.

In the U.S., federal officials say there are no plans to make them broadly mandatory. In some states, Republican governors have issued orders barring businesses or state agencies from asking people to show proof of vaccination.

Objections revolve mostly around privacy and security - how people’s personal information will be stored - and fairness. Critics say the passports will benefit people and countries with more access to vaccines.

Supporters say they could make reopenings faster and easier. Proof of vaccination or a negative test could be a way for businesses and schools to reassure customers, students and parents that steps are being taken to limit transmission of the virus.

International travel bans by countries could also be eased if people are able to show proof they’re vaccinated. Some countries have long had requirements to prove vaccination against yellow fever.

Still, a challenge is creating certification systems that work across vaccine providers and businesses. More than a dozen initiatives are underway to develop a credential that could be stored on a smartphone or printed on paper, using a QR code.

The AP is answering your questions about the coronavirus in this series. Submit them at: FactCheck@AP.org.