How safe is it for vaccinated people to return to in-person work? An expert weighs in

By Katia Hetter, CNN

    (CNN) -- The US Centers for Disease Control and Prevention has changed its guidance to once again recommend that even vaccinated people start masking indoors in areas of the country with high and substantial coronavirus spread. Key to their decision was a study that shows that fully vaccinated people can still transmit the Delta variant.

At the same time, Disney, Netflix, Google, Walmart and the federal government announced plans to implement some type of vaccine requirement for employees returning to in-person work.

Is it safe for vaccinated people to return to work if vaccine mandates are in place? What if they are not -- is masking enough, and what if others around you are unvaccinated and not wearing masks? What about workers who have children too young to be vaccinated?

To help us navigate these uncertain times, we turned to CNN Medical Analyst Dr. Leana Wen. 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 author of a new book, "Lifelines: A Doctor's Journey in the Fight for Public Health."

CNN: We know that breakthrough infections can happen. How does it help to have vaccine mandates at work if the vaccinated can also spread Covid-19?

Dr. Leana Wen: Vaccine requirements will help make workplaces much safer for everyone. Here's why. There is a lot of misunderstanding about what the CDC's new data is showing. The agency found that vaccinated people infected with Covid-19 may carry just as much virus as those who are unvaccinated and have Covid-19.

However, the chance of actually contracting Covid-19 is greatly reduced if you're vaccinated. According to Dr. Anthony Fauci, you have an estimated eight-fold reduction in risk of having coronavirus if you're vaccinated compared to if you're not -- and an estimated 25-fold reduction in risk of having severe enough disease to cause hospitalization and death, which is truly remarkable.

Put a different way, if I have to spend time in an enclosed, indoor space with someone, the chance of that person having coronavirus and potentially being able to infect me is an estimated eight times less if they are vaccinated. That's why vaccine requirements at work make sense. It dramatically reduces the chance that your coworkers could be infected. And because you are vaccinated, too, your chance of getting Covid-19 from them is also reduced an estimated eight-fold from if you were not vaccinated.

Could it be possible that someone has coronavirus, and you still contract it from them? Yes. The higher the coronavirus transmission rate in your community, the more likely someone has Covid-19, even if they are vaccinated. However, it is much safer to share space with people when everyone is fully vaccinated.

CNN: What if the workplace allows people to opt out of vaccination through testing?

Wen: It depends on how frequent the testing is. Testing is not a strategy that prevents someone from contracting Covid-19. However, if there is frequent testing, it could pick up on infections quickly and prevent that person from spreading it. I'd feel more comfortable with twice-weekly testing than weekly testing. Either the antigen test or PCR test should be fine, as long as it's authorized by the FDA.

Test less frequently and I think you get into a situation of false reassurance. Just because someone tested negative a week ago doesn't mean that they couldn't have contracted coronavirus in the meantime. And if they are unvaccinated, they have a higher chance of getting Covid-19 and therefore of passing it on to you.

CNN: Should workplaces require both vaccinations and masking?

Wen: This is an interesting question, and one that the CDC has not really weighed in on. Right now, the CDC is saying that indoor masking should occur in areas of high or substantial Covid-19 transmission, and they are not saying that if everyone is vaccinated, masks are no longer needed.

I think this is a mistake. The risk of vaccinated people transmitting to other vaccinated people is low. At some point, we have to accept that we're not going to get zero risk. Workplaces need to protect their employees, and a vaccine requirement is a very good level of protection. If a workplace truly has an enforced vaccine mandate with proof of vaccination, I think they could make masking optional instead of required.

That said, some individuals may choose to be more careful at work. That's also completely understandable. I hope that workplaces allow accommodations to be made. For example, there may be some people who are immunocompromised. They may not want to sit in a crowded conference room with maskless -- but vaccinated -- peers, because even a small risk to them is too much. I hope employers will allow such employees to work from home, or to be in a separate physical space and to call in to virtual meetings. Of course, not all workplaces can reasonably make these accommodations, and this is once again why vaccine requirements are so important. They reduces risk substantially.

CNN: What if a workplace doesn't require vaccines? Is masking enough? Or what about places that don't require either?

Wen: A workplace that doesn't require vaccines but continues to abide by strict masking and distancing, and has good ventilation, is also pretty safe. Adding testing on top of that will be a helpful additional layer of protection. The quality of the mask matters -- in these situations, people should at least wear a three-ply surgical mask. And it's important that everyone consistently wears their mask -- not dangling around the necks, but fully covering their nose and mouth.

If the workplace doesn't require vaccines or masks, and you know that you are surrounded by maskless people who are probably unvaccinated, that's a much riskier situation for you. Know that you are still well-protected from severe illness; but depending on the infection rate in the community around you, you could be at risk of a breakthrough infection.

Try to take steps to protect yourself. Wear an N95 or KN95 mask when in close proximity indoors with these maskless people of unknown vaccination status. Try to stay distanced from them, and if possible, ask for accommodations to sit in a separate space. Open the window and door to increase air flow. Stay out of crowded gathering areas like breakrooms and cafeterias. Know that risk is cumulative. The more people you are exposed to, the higher your risk.

You could also see whether other employees feel as you do. More and more workplaces are implementing vaccine requirements -- or at least a testing requirement. It's possible at your workplace that those who want these mandates are in the majority. Your voices need to be heard, and they could make a difference.

CNN: What's your advice for parents of young kids or people living at home with immunocompromised family members? Should they try to keep working from home?

Wen: This is really tough. Many people are in this situation where we may not be so concerned about a breakthrough infection to us, because chances are it will be mild, but we are very concerned about potentially being a carrier who could infect those we live with.

Taking precautions at work is important. Vaccine requirements would make me feel much safer. I'd be comfortable going to work, and not wearing a mask, if everyone around me is guaranteed to be fully vaccinated. I'd probably still try to stay out of the highest risk settings, like cramped, poorly ventilated conference rooms where dozens are sitting shoulder-to-shoulder for hours at a time.

If I'm not certain that the others around me are vaccinated, I would make sure to wear a high-quality mask when around them indoors. Other people will be even more cautious. Someone who lives at home with an elderly parent on immunosuppressant medications may want to follow the CDC guidelines to the letter and wear a mask even if everyone around them is known to be vaccinated. Still others may choose to work at home if that's an option available to them. We all have different tolerance of risk, and I hope companies will try to make reasonable accommodations for people's living situations.

This is a very confusing time for everyone. It feels like the US has taken a step backward in our fight against the pandemic, and we have. The Delta variant has changed things again. We need to keep being vigilant, reassess our own risk and our family's, and keep in mind that vaccination remains key to protecting ourselves and our loved ones.

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