De-escalation measures after confinement to stop the transmission of SARS-CoV-2 coincide with the arrival of good weather, and many people wonder if, as with other viruses, doing more outdoor activities can contribute to cut the spread of the disease.
In recent weeks, various studies have been published in this regard on medical platforms that distribute manuscripts pending publication in scientific journals. They are, therefore, preliminary results, but they are already giving an idea of something that a priori seems logical: in closed spaces the probability of being in contact, and with greater intensity, with SARS-CoV-2 is much greater than at fresh air. For example, one of these studies, carried out in Japan, indicates that the risk of contagion is up to 19 times higher indoors. In another of the studies, this one based on cases from China, it was shown how the infections had mainly occurred in private homes and on public transport.
“The model that helps us better understand this is that of the influenza virus, which is the one that we have more information about.”, Explains Vicente Soriano, researcher and professor at the Faculty of Health Sciences of the International University of the Rioja. “Basically, the main source of transmission is small droplets that we emit when singing, talking, sneezing or coughing. In addition, you have to take into account the amount of virus you are exposed to: if someone coughs you right in front of your face, it will be much easier for them to infect you and, also, to do so in a much more serious way. When one interacts with other people in an open space, the droplets disperse more easily, and the possibility of concentration of these infective particles where the viruses are found is very low compared to a closed place ”, the expert explains.
Ultimately, what determines the possibility of becoming infected and also the severity with which the disease develops is not only the fact of being in contact with the virus but also the amount of virus to which one is exposed, that famous’ load viral’.
“We have studied all this very much with the flu and other viruses, now it is necessary to verify it with the SARS-CoV-2 in particular, ” explains Soriano, whose team has carried out other preliminary work that describes several cases of groups of infection by SARS -CoV-2 in Madrid. “At the beginning of March ten people met in a closed space for a working discussion, and one of them had been in Milan in the previous days”, the researcher explains. “All ten of them were infected, and one of these people was admitted to intensive care within five days of contact. On the contrary, another of the groups studied was a community of 25 religious who live on the outskirts of Madrid, in a building with high ceilings and many outdoor spaces. Of the 25, who are also cohabiting, one of them was infected in the days prior to confinement. Antibody detection tests revealed that 21 of them became infected, but none of them developed a serious condition, and that there was even an 80-year-old woman in the group “.
The results, although also preliminary and in small samples, confirm that the amount of viral inoculum received at the time of exposure can determine the course of the evolution of the disease. A closed environment with several people arguing without maintaining physical distance or wearing a mask seems the perfect breeding ground for the transmission of the virus.
Better in open spaces?
In view of these signs, it seems much more likely to be infected in closed spaces, although it is always necessary to keep the distance measurements and use a mask when this is not possible. The arrival of good weather and outdoor meetings should help keep the epidemic at bay and, on the other hand, Soriano reminds us that, after weeks of confinement, the current number of active people who can infect others should be very small. Of course, we must not lower our guard: ” To avoid outbreaks, we must continue avoiding crowds, keeping distances or wearing a mask if this is not possible, and people with symptoms should stay at home “, insists the expert.
Be cautious, but also calm. For example, we should not be overwhelmed if a runner passes us with agitated breathing and without a mask, since in those two seconds the probability of contagion should be very small, but there is no neglect of the basic measures to protect yourself recommended by the authorities. sanitary.
