How safe is the return to face -to -face work for a person?An expert responds

(CNN) -- The US Centers for Disease Control and Prevention (CDC) has revised its guidance to once again recommend that even vaccinated people start wearing masks at home. the interior in areas of the country with a high and considerable spread of the coronavirus. The key to his decision was a study showing that fully vaccinated people can continue to transmit the delta variant.

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

Is it safe for vaccinated people to return to work if vaccination requirements apply? And if they are not? Is mask wearing enough, and what if others around you are not vaccinated and are 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 is also the author of a new book, "Lifelines: A Doctor's Journey in the Fight for Public Health."

CNN: We know that post-vaccination infections can occur. What good is it that vaccines are mandatory if those vaccinated can also spread covid-19?

Dr. Leana Wen: Vaccination requirements will help make workplaces much safer for everyone. Here's why: There are a lot of misunderstandings about what the new CDC data shows. The agency found that vaccinated people infected with covid-19 can carry the same amount of virus as unvaccinated people with covid-19.

However, the chance of actually contracting covid-19 is greatly reduced if you are vaccinated. According to Dr. Anthony Fauci, the risk of contracting the coronavirus is estimated to be eight times lower if you are vaccinated than if you are not, and the risk of illness severe enough to cause hospitalization and death is estimated to be it is 25 times less, which is really remarkable.

In other words, if I have to spend time in a closed space, indoors, with someone, the chance that person has the coronavirus and can infect me is about eight times less if they are vaccinated. That's why workplace vaccination requirements make sense. This drastically reduces the chance of your coworkers getting infected. And since you are also vaccinated, your chance of getting covid-19 from them is also reduced by approximately eight times compared to if you were not vaccinated.

Is it possible for someone to have the coronavirus and you to catch it from them? Yes. The higher the rate of coronavirus transmission in your community, the more likely it is that someone will have 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 getting vaccinated if they get tested?

Wen: It depends on the frequency of testing. Testing is not a strategy to prevent someone from contracting covid-19. However, if the tests are frequent, they could quickly detect infections and prevent that person from spreading them. I would be more comfortable testing twice a week than weekly testing. Both the antigen test and the PCR test should be fine, as long as they are authorized by the FDA (United States Food and Drug Administration, in Spanish).

If you test less frequently, I think you are entering a false security situation. Just because someone tested negative a week ago doesn't mean they haven't been able to catch the coronavirus since then. And if they are not vaccinated, they are more likely to contract covid-19 and, therefore, to infect it.

CNN: Should workplaces require both vaccination and mask use?

Wen: This is an interesting question, and one that the CDC hasn't really considered. At this time, the CDC is saying that indoor mask wearing should occur in areas of high or substantial covid-19 transmission, not saying that if everyone is vaccinated, masks are no longer necessary.

I think this is a mistake. The risk of transmission from vaccinated persons to other vaccinated persons is low. At some point, we have to accept that we are not going to achieve zero risk. Workplaces have to protect their employees, and requiring a vaccine is a very good level of protection. If a workplace actually has a vaccination with proof of vaccination mandate, I think they could make wearing a mask optional instead of mandatory.

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

CNN: What if a workplace doesn't require vaccinations? Is the use of the mask enough? Or what about places that don't require any?

Wen: A workplace that doesn't require vaccinations, but still adheres to strict masking and distancing, and has good ventilation, is also quite safe. Adding the tests on top of that will be a very useful extra layer of protection. The quality of the mask is important: in these situations, people should wear at least a three-layer surgical mask. And it is important that everyone wears the mask consistently, not hanging around the neck, but completely covering the nose and mouth.

If the workplace doesn't require vaccinations or masks, and you know you're surrounded by people without masks who probably aren't vaccinated, that's a much riskier situation for you. Keep in mind that you are still well protected against serious illness, but depending on the infection rate in the community around you, you could be at risk of a post-vaccination infection.

Try to take steps to protect yourself. Wear an N95 or KN95 mask when around these people without a mask and with unknown vaccination status. Try to stay away from them and, if possible, ask permission to sit in a separate space. Open the window and door to increase airflow. Stay away from crowded gathering areas, like break rooms and cafeterias. Keep in mind that the risk is cumulative. The more people are exposed, the greater the risk.

You can also see if other employees feel like you. There are more and more workplaces that impose the obligation to get vaccinated, or at least to undergo a test. It is possible that in your workplace those who want these mandates are in the majority. Their voices need to be heard and could make a difference.

CNN: What is your recommendation for parents of young children or people living at home with immunosuppressed family members? Should they try to continue working from home?

Wen: This is really hard. A lot of people find themselves in this situation where we may not be as concerned about a post-vaccination infection for ourselves, because it's most likely going to be mild, but we are very concerned about potentially being a carrier that could infect those we live with.

Taking precautions at work is important. Requiring the vaccine would make me feel much safer. I would feel comfortable going to work, and without wearing a mask, if everyone around me guarantees that they are fully vaccinated. I would probably still try to stay away from higher-risk environments, like stuffy, cramped conference rooms where dozens of people sit shoulder to shoulder for hours.

If I am not convinced that the people 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 living at home with an elderly parent who is taking immunosuppressive medications may want to follow CDC guidelines to the letter and wear a mask even though they know everyone around them is vaccinated.

Others may choose to work at home if it is an option available to them. We all have different tolerances for risk, and I expect companies to try to make reasonable adjustments for people's life situations.

This is a very confusing time for everyone. It seems that the United States has taken a step back in our fight against the pandemic, and it has. The delta variant has once again changed things. We need to continue to be vigilant, reassess our own risk and that of our family, and keep in mind that vaccination remains key to protecting ourselves and our loved ones.