The word itself says it, of course: asymptomatic, that is, without symptoms. It means that if we are in close contact with a person who has Sars Cov-2 and who has not swabbed, we will never know that that person is a potential source of contagion and, consequently, can be a serious danger to us. . However, what we can know today is what the real danger is of those who have the virus but do not have the symptoms and what probability we have of contracting that type of coronavavirus from an asymptomatic.
From February to today, science has taken steps like a tripper. And he is able to explain, in enough detail, who are asymptomatic, how many are compared to who has symptoms and what their real viral load is. And among the “it is said”, the seems and the hearsay, science tries to make a minimum of clarity. The World Health Organization itself, by voice
What do we know about the asymptomatic
Meanwhile, we make a distinction between asymptomatic (those who just do not have any type of symptom, are fine and do not have any alarm bells), the paucisymptomatic, that is, who have various kinds of ailments but still mild (they have neither fever nor cold ) and the pre symptomatic. Who are the latter? Basically those who have contracted the virus but haven’t developed symptoms yet. The same virologist and head of the infectious diseases department of Amedeo di Savoia, Professor Giovanni Di Perri in an interview with the La Stampa website he had explained that “contagion often occurs by pre-symptomatic patients”. They are people who have contracted the virus, do not know it and lead a normal social life before the onset of symptoms which usually occurs a couple of days later.
Perhaps it is also for this reason that there is a tendency to confuse with numbers and percentages and to say that, today, among those who contract coronaviurs, over 80% are asymptomatic. It wouldn’t be like that.
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One explains it to us recent analysis of Medicine and Microbiology which compared 13 studies involving 21,708 people. The analysis, also published by Focus magazine, lets us know that one in five of those who have contracted the virus are asymptomatic, 17% of cases. The scientists considered people who had shown no symptoms for at least 7 days from the positive swab to be asymptomatic. «The diagnosis – explain the scientists in their report – in all studies was confirmed using an RT-PCR test. The percentage of asymptomatic cases ranged from 4% to 41%. The meta-analysis (fixed effect) found that the percentage of asymptomatic cases was 17% (95% CI: 14% -20%) overall; higher in the cases of elderly people (14% -27%), and lower among the youngest (13% -20%) ». Again the analysis: «Five studies have provided direct evidence of the direct transmission of the infection from asymptomatic cases. Overall, the relative risk of asymptomatic transmission was 42% lower than symptomatic transmission ”. But another study conducted in Switzerland, carried out in Geneva among people living together, also tells us: the risk of an asymptomatic passing the virus to a family member would be equal to a quarter of the risk run by a symptomatic.
How an asymptomatic should behave
Again, science comes to our aid. To calculate the probability of contagion of people present in risk situations, a group of scientists, led by Professor José Luis Jiménez, of the University of Colorado, used a simulator, created with the intention of showing the importance of the factors that hinder contagion through aerosols. Scientists have reconstructed how the virus is transmitted through infectious droplets (the droplets that travel through the air and produced by simple breathing or, more quickly, by a sneeze, a cough, or by someone who screams or sings) in a room. closed.
