To take masks outdoors, we must reinforce use indoors - 10/13/2021

The news that the states of São Paulo and Rio de Janeiro are discussing the end of the obligatory use of masks in open places has brought great fear to the population. Is it time we left the masks? Isn’t it too early to do it safely?

In May of this year, the US Center for Disease Control and Prevention (CDC) announced that vaccinated people would no longer need to wear masks. Two months later, given the circulation of the delta variant and the refusal of much of the American population to get vaccinated, the country saw the number of cases and deaths soar.

The CDC backtracked on the orientation, but the damage was already done, and the agency was accused of having left science aside in the name of pressure for the resumption of economic activities.

The episode served as a warning to the world. Removing the recommendation to wear masks too soon could put months of effort to control the pandemic at risk.

However, it is part of good communication in health emergencies to clearly inform the risks so that people can manage their individual risks based on data.

For this, it is important to know that there is no zero risk. Anyone who needs to live socially in the midst of a pandemic of a highly contagious respiratory virus will be at risk. Therefore, knowing more or less risky situations is essential for the population to make good decisions.

We now know that Sars-CoV-2, the virus that causes covid-19, basically passes through the air. This means that being indoors, especially when there are crowds, is very unsafe. Places like this demand good quality masks, such as PFF2, those whose elastic goes behind the head.

On the other hand, the risk of being contaminated outdoors is extremely low. According to biomedical engineer Vitor Mori, a researcher at the University of Vermont, USA, it is estimated that less than 1% of transmissions occur in these spaces.

Today, Brazil has about 45% of the population fully vaccinated. It is not yet a rate that allows us to put aside preventive measures, but it does allow us to start thinking about some flexibility.

Thus, it is natural that the discussion about the end of the use of masks starts in open environments, in places where it is possible to maintain a distance between people, since face-to-face interactions and for prolonged periods increase the risk of contamination. When it is not possible to maintain physical distance, the ideal is to wear a mask.

Mori defends that the flexibility of the use of masks outdoors should be accompanied by the reinforcement, by political and health authorities, of their need in closed places.

For some reason that escapes my understanding, many people think that when entering a closed and crowded restaurant, the mask becomes unnecessary. I also don’t understand why some people think that being in a closed room with friends and family without a mask is not dangerous. Do they think that only strangers transmit the virus?

Unventilated places pose a high risk to people, and leaving the mask in these spaces will likely be the last step after the end of the pandemic.

Another confusion is related to the risk of transmission between vaccinees. Although it exists, we know that those who are immunized are much less likely to become infected and develop serious conditions than those who have not had the vaccine.

If we do not make this distinction and say that vaccinated and unvaccinated people transmit the virus equally and that open and closed places present the same risk of contamination, and that is not true, why would people then be vaccinated and opt for air spaces free for social gatherings?

I don’t agree with those who think that people cannot make good choices. They do, however, need information. Knowing that the vaccine is essential to contain the pandemic, that the virus passes through the air and that, therefore, closed and unventilated places are more risky than outdoor spaces helps in decision-making.

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