Colored, with drawings or with our printed photo, for many the masks have become, as well as a habit, a decorative accessory. And science tells us we shouldn’t abandon them even now, even if the circulation of the virus is less and vaccination coverage has increased.
A study conducted by the University of California at Berkeley tried to quantify – a daunting task – the benefits of non-drug interventions against the coronavirus, including face masks, spacing and frequent hand hygiene.
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The result? In cases of contact with a positive, the use of the mask reduced the probability of becoming infected by an average of 48%. This data is an average that applies to a large sample of individuals, both unvaccinated and vaccinated. The research, still not revised with the peer reviewing process, has been anticipated on the medRxiv platform, but we will have to wait for the official publication to confirm the details.
When the risk is greatest
The study took place from February to September 2021 and involved more than 2,500 volunteers in California who were swabbed to check for Sars-Cov-2. Of these, 1,280 tested positive. All the participants, both those who had had Covid-19 and the others, provided information on any contacts at risk in the 14 days prior to the test, on the duration and characteristics of the meeting (indoors or outdoors, with internal people or outside your family unit).
Very often, in 82% of cases, those who reported having had a risk contact did not wear a mask. In addition to quantifying the effectiveness of this device, the research focuses on which exposures were riskier on average. In particular, the probability of becoming infected is almost 3 times higher when the positive is a cohabitant, 2 times higher when the meeting takes place indoors and about 2.6 times greater when it lasts from 3 hours upwards. Therefore, be careful also to risky contacts in the office, at school and at home. Obviously, the risks are lower for those who are at least partially vaccinated (68% lower) and for those who have completed the vaccination cycle (-77%) than for those who have not had any dose.
“The study – he comments Paolo Villari, Professor of Hygiene at Sapienza University of Rome, not involved in the work – provides new statistical evidence and confirms the significant role of non-pharmacological interventions against Covid-19 “.
In the face of the great effort and merit of translating these risks into numbers, some scientists have expressed some perplexities, described in an article on Nature, on how the statistical study was built. In particular, the research compares the situation of each infected person with that of a subject, called “control”, of the same age and sex but not positive and someone has doubts about this type of approach. The other element of discussion concerns the fact that research began before the spread of the delta variant, which partly changed the characteristics of the epidemic.
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Because removing the mask is a mistake
The message of the research is that, in the face of the reopening, some precautions must be maintained. The reasons are varied. “Vaccines are highly protective against Covid-19 disease in the symptomatic form – underlines Villari, who is also Director of the Department of Public Health and Infectious Diseases of Sapienza – but they do not always prevent contagion and therefore do not completely block the circulation of the virus” . Furthermore, some people are not yet immunized (or not fully) and others are waiting for the third dose, remembering that immunity is not forever. “Furthermore, it is true that vaccination is very effective, but not 100% – remarks the expert – and there is a very small proportion of people who do not develop an adequate immune response. For all these reasons, the small effort to maintain the protective measures provide support to defend ourselves and others, especially the most fragile “.
Not just a mask, the 4 essential measures
The use of the mask is not the only good habit to keep, but today we don’t have to invent anything. “Even today, for the reasons mentioned, it is important to keep your distance, especially if indoors or in a crowded environment. And wash your hands often and carefully, even with sanitizing gels if we do not always have soap and water available”.
Where spacing is not possible, the bezel becomes even more important, but the reverse also applies. “The idea is that the more measures we take, the better”, recalls the expert, but the opposite is also true: one is better than zero. Finally, the fourth measure, no less central than the others: staying at home if you have fever or respiratory symptoms. “Following the rules is not a big effort, concludes the expert, and it is a small price to return to a working, social life. and fuller affective.