For the WHO, becoming infected with asymptomatic drugs is a rare possibility and is not among the main ways of contagion. This claim, always supported by other authorities, does not agree with some scientists, according to whom asymptomatics are rather contagious. We will need to collect more data.

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The contagion from asymptomatic but positive people to the new coronavirus is “rare or very rare” : these are the latest statements of the World Health Organization (WHO), in the conference of 8 June, which, however, not all scientists agree . From the beginning, the WHO and the Higher Institute of Health have argued that asymptomatic contagion is not one of the main ways of transmitting the virus and there has been no change of ideas on this point. However, some scientists raise doubts claiming that asymptomatic infections are possible and not rare.

Asymptomatic, contagion is rare for the WHO

At the beginning of the epidemic, the WHO explained that the infection occurs mainly from people with fever, cough and other common symptoms, even if in a mild form. According to what is already known about other coronaviruses ( Sars-Cov-1 , the cause of Sars, and the virus responsible for Mers), transmission from asymptomatic is possible but infrequent. Although some studies report that you can be infected with people who have no symptoms , as the WHO recalls , the frequency with which this occurs was not known at the beginning of the epidemic, and is still unknown. further details.

To date there is not enough evidence to change this idea: for this reason in the conference of 8 June 2020,Maria van Kerkhove , WHO epidemiologist and technical manager, reiterated that, although continuous monitoring of the various cases continues, asymptomatic transmission is still “very rare” . “It is still an open question, however,”  clarified Van Kherkhove, who points out that ” WHO continues to collect data and analyze it to accumulate further evidence . ”

Not only the WHO, but also other health authorities, such as the European Center for Disease Prevention and Control and the Higher Institute of Health, since the early stages of the spread of Covid-19, have remarked that this path of infection seems less probable and not among the main ones. Among the reasons there may also be the fact that if you have no symptoms and therefore if you do not sneeze and do not cough, it is more difficult for the droplets of saliva containing the virus – the famous droplets – to be transmitted and infect other people.

The criticisms

But not all scientists agree with the WHO statement and some experts reiterate that transmission from asymptomatic is possible and that therefore it is not the case to lower your guard. Among these, the virologist Andrea Crisanti of the University of Padua who in a comment on AdnKronos criticized the WHO statement. The expert refers to the example of the study in Vo ‘Euganeo , a municipality heavily affected by Covid-19. Data on several thousand people showed that about 43% were asymptomatic and contagious like symptomatic ones .

In the research, 8 cases appeared between two different shots of the study, of which 5 asymptomatic. In 2 cases it was not possible to reconstruct the chain of infection, in 3 cases it occurred from symptomatic family members and in 3 cases from asymptomatic ones. The statistics are still very small but would indicate that asymptomatic contagion is not non-existent or very rare.

Everything is perhaps in understanding what is meant by “rare” , the word used by WHO , and other studies will be needed to accumulate data and have more evidence and more data, which are still not enough, even if they will be limited to a specific geographical area .

Moreover, we must also understand what is meant by asymptomatic : in this case we are talking about people who despite having the virus will never develop the disease and have no symptoms. But even those who have been infected and will have the disease for a period of time – incubation – are asymptomatic: studies have estimated that in these cases the person is contagious about 2-3 days before the first symptom appears. And even after clinical healing , you can be asymptomatic but still positive for the virus. In this case it is necessary to wait for the negative effect of the swab , even if research shows that if you have not had any symptoms for at least 3 daysand the first clinical manifestation occurred more than 10 days before it is reasonable to think that the probability of transmitting the virus is very low.