Bars and restaurants, gym classes, religious services, public transport … all these areas are sources of new coronavirus infections , according to a new study (preprint).
In the medium term, then, we have to focus these activities more towards the outside than the inside, since almost all the outbreaks studied in China (318) only 2 took place outdoors .
It is important to understand where and how SARS-CoV-2 is transmitted to maintain a low rate of contagion so as not to saturate the health system. So China is paying particular attention to how new cases are born now that containment restrictions have been relaxed .
In the cited study, case reports were drawn from the local Municipal Health Commissions of 320 municipalities in China, not including Hubei province, between January 4 and February 11, 2020 . All the outbreaks that involved three or more cases were identified and the main characteristics of the closed spaces in which the outbreaks were reported and the associated internal environmental problems were reviewed.
In this way, 318 outbreaks with three or more cases were identified, involving 1,245 confirmed cases in 120 cities . The locations where the outbreaks occurred were divided into six categories: homes, transportation, food, entertainment, shopping, and miscellaneous.
Among the identified outbreaks, 53.8% involved three cases, 26.4% involved four cases, and only 1.6% involved ten or more cases. Outbreaks at home were the dominant category (254 of 318 outbreaks; 79.9%), followed by transportation (108; 34.0%; many outbreaks involved more than one category of location). Most of the outbreaks in the home involved three to five cases.
A single outbreak was identified in an outdoor environment , involving two cases.
In conclusion, all the identified outbreaks of three or more cases occurred indoors, confirming that sharing indoor space is a significant risk of SARS-CoV-2 infection.
The reason that outdoors is more unlikely is that the safety distance between people is easier to carry out (about two meters). This virus spreads through the ‘droplets’ that come out of our mouth or nose when we cough or sneeze , and to a lesser extent when we speak, and that end up inside another person through the air directly, where this virus can endure up to three hours, or through hands that carry the virus by touching a contaminated spot.
According to Harvard biologist Matthew Meselson , there are differences between the inside and the outside. Inside, he recommends not entering any space in which we believe that there is an infected person, but outside he ensures that two meters can be a good measure because ventilation disperses any droplets that may be in the environment much earlier.