CNN  — 

The US Centers for Disease Control and Prevention announced that people fully vaccinated against Covid-19 do not need to wear masks or practice physical distancing in virtually all indoor and outdoor settings.

This was an abrupt shift from the CDC’s previous guidance, which had detailed color-coded pictures that many criticized as being too confusing and too strict. Previously, vaccinated people were urged to wear masks in some outdoor settings such as crowded get-togethers and most indoor settings, such as worship service, the gym and restaurants.

Now, people who are fully vaccinated don’t need to wear masks in these settings, though they still are required to on buses, trains and planes and in hospitals. Unvaccinated people and those with a weakened immune system should still wear masks, the CDC says.

How do people know who’s vaccinated and who’s not? What if some people still want to wear masks? And what about people who are not yet vaccinated, like young children?

We turned to CNN Medical Analyst Dr. Leana Wen to see what to do next. Wen is an emergency physician and visiting professor of health policy and management at the George Washington University Milken Institute School of Public Health. She’s also the author of the forthcoming book “Lifelines: A Doctor’s Journey in the Fight for Public Health.”

CNN: What do you think of the CDC’s Thursday decision on masking?

Dr. Leana Wen: Frankly, I was shocked. For months, I’ve been pushing for the CDC to give clearer, more practical guidance on what fully vaccinated people could do. They’ve been moving so slowly and cautiously, and I expected for them to say something like, fully vaccinated people can now get together with other fully vaccinated people, not just in informal settings like small dinners at home but formal settings like workplaces — I was thinking a conference room where fully vaccinated colleagues can all take off their masks.

Pedestrians walk on the pier in Santa Monica, California, on May 13, when the CDC announced vaccinated people can go maskless in most outdoor and indoor settings.

Instead, the CDC removed virtually all restrictions on fully vaccinated people. On the one hand, this is a great affirmation of just how effective the vaccines are. I do think there is a great story to tell, that the vaccines are so powerful at protecting against illness and preventing vaccinated people from spreading coronavirus. On the other hand, this is such a sudden reversal. I don’t think people fully understand why the change was made — it feels like we went from zero to 100 overnight.

My concern is not for those who are fully vaccinated. Those people are well protected (with the exception of individuals who are immunocompromised). My concern is for those who are not yet able to be vaccinated, who are now potentially exposed to a higher level of risk because they will be around unvaccinated people who choose not to wear masks.

That’s because we can’t possibly know who’s vaccinated and who’s not. If you’re in a grocery store, and most people aren’t wearing masks anymore, what if some people aren’t vaccinated? If you yourself are vaccinated and pretty healthy, this is not a problem for you. But what if you’re not vaccinated — not because you don’t want to, but because you can’t?

I have two little children, ages 1 and 3, who can’t yet be vaccinated. Or what if you’re immunocompromised and the vaccines may not protect you as well, so you still have to be careful, even if you keep your mask on? I’m worried that the new CDC guidelines make it less safe for those who are already more vulnerable.

CNN: When should people who are vaccinated wear masks?

Wen: The CDC requires that people wear masks in planes, trains and other public transportation, regardless of vaccination status. They should also keep wearing masks in high-risk settings like nursing homes, hospitals and prisons. And they should follow the law of their state and local officials, as well as abide by any rules set by individual businesses.

We need to have a bit more nuance than this. I’d encourage people to consider their own medical risks. If they are being treated for cancer and are on chemotherapy, or an organ transplant patient on immunosuppresants, I agree with the CDC that these people really need to keep masking in public settings if they are around potentially unvaccinated people. The chance of your carrying Covid-19 and transmitting it to others is also much decreased if you’re vaccinated, but that risk is still there. If you live at home with someone who is vulnerable, you may also want to use some additional caution.

In my case, I’m healthy but I live with two unvaccinated children — they can’t be vaccinated yet. I’d probably still be a bit cautious. I certainly wouldn’t need to wear a mask outdoors, but if I’m in a full-capacity, indoor church service where everyone is singing, and I’m not sure that people around me are vaccinated, I’d probably still wear a mask. Others may make a different choice, and that’s OK.

CNN: What about unvaccinated people? When should they wear masks?

Wen: Unvaccinated people must still wear masks whenever they are spending time around someone who is unvaccinated or people of unknown vaccination status. If they are around someone who is definitely vaccinated, they don’t need to mask. But if they are in public, and it’s not clear if people around them are vaccinated, they should wear a mask.

The key is that vaccinated people are well protected, but the unvaccinated are not. The danger to them is not from the vaccinated, but from others who are not yet vaccinated. My concern with the CDC guidelines is that they don’t distinguish between who’s vaccinated and who’s not.

The unvaccinated are now at higher risk, because previously people around them were masked, and now some others who are unvaccinated may be unmasked and not keeping up with distancing.

CNN: What if people have underlying conditions or are somehow immunocompromised? What should they do?

Wen: Those who have underlying medical conditions should be vaccinated. The vaccine may not provide them with optimal protection, but it will provide them with some, and it’s especially crucial for these individuals to get that protection.

I’d advise that they continue to use an abundance of caution, recognizing that their level of immune protection may not be as high as others without their condition. If they are around people who are potentially unvaccinated, they should keep masking and distancing.

CNN: If fully vaccinated people live with unvaccinated people who are at high risk for serious disease and death from Covid-19 – because of diabetes, heart disease, any other compromising condition – should fully vaccinated people still go maskless in places where they are allowed to?

Wen: This is a really tricky situation. Your chance of contracting Covid-19 if you’re vaccinated is very low, and your risk of passing it on is even lower. But it’s not zero.

The best thing to do is to try to get these individuals who are at high risk for severe outcomes vaccinated. This may not always be possible – for example, children under age 12 can’t yet get vaccinated. If high-risk individuals are vaccinated, you can breathe a sigh of relief because at least they have some protection. If they are unvaccinated, though, you might still want to use caution.

With my family, if it’s indoors and without masks, I am still choosing to see only fully vaccinated people. I just wouldn’t feel comfortable, say, going to a packed exercise class with other maskless people who are potentially unvaccinated. After being careful for so long, I wouldn’t want to risk the small chance of bringing back coronavirus and infecting my 1-year-old.

CNN: Some people are very nervous going into crowded places now, especially if people are unmasked. What would you advise them to do?

Wen: I really understand where they are coming from! It’s been a traumatic time for all of us, and for many, it will take time to ease back into our old routines.

That’s another reason I wish the CDC was less abrupt with their guidance. They should give us time to adjust to a new normal. Wait until infection rates decline more, then ease the guidance.

It’s completely OK for people to take things at their own pace. If you’re nervous about seeing random maskless strangers in crowds, start with seeing people you know and love, indoors, without masks — ideally people who are also fully vaccinated. Work your way up. Perhaps take your mask outdoors on walks, and, if you wish, indoors in settings where you can still keep physical distancing. Even though it’s safe for you to do something doesn’t mean that you need to. If you still wish to avoid crowds of possibly unvaccinated people, it’s absolutely your right to do so.

CNN: What if you still have unvaccinated children, including those under age 12, who can’t get the vaccine yet?

Wen: This is a big reason I don’t like the CDC guidance. It puts our children at higher risk to now be around adults who may or may not be vaccinated.

Every family needs to decide the level of risk you are willing to tolerate for your children. It’s true that kids tend to get much less severely ill from Covid-19 than adults, but children can and do get ill. For our family, we are fine with our kids playing outdoors with other kids, without masks, but indoors, they should still wear masks if there are adults or children around them who are unvaccinated. And we, as vaccinated parents, still take extra precautions that we wouldn’t if not for the kids.

CNN: How much longer are we going to be in this strange state of not knowing what to do?

Wen: We are in this strange in-between place for sure. The CDC has made things clearer in some ways, but I think also more confusing in others. The way that I interpret the guidelines is that it’s really now up to us. We have to decide what level of risk we are comfortable with for ourselves and our families. There is no one-size-fits-all answer. We need to decide what’s most important to us.