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How does the infection spread. The ‘engine’ that drives the Covid-19 pandemic is made up of numerous parts and mechanisms: coexistence under the same roof, group activities, crowded environments, but also elusive asymptomatic, superdiffusori and contexts that amplify infections. To analyze them one by one they are experts from Johns Hopkins University in Baltimore, in an article published in Science. By reviewing the latest scientific evidence, the researchers point out how most infections occur at home: Cohabitants have a six times greater risk of being infected than other close contacts.
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The most exposed are the spouses of the sick and the elderly who live in a family with younger people. The risk is also high in hospitals, nursing homes, dormitories and prisons, where contacts are repeated and close, generally between older people. At the community level, the transmission of the infection is greatly affected by the action of the asymptomatic, who continue to circulate compared to the sick despite having a comparable viral load.
The spread of the virus can become overspread in particular contexts., as in choirs, department stores and religious events, where people have a closer contact in a short period of time. There are also contexts where transmission can be amplified if several infections occur one after another in rapid succession, as has already been seen in slaughterhouses, churches and schools.
The amplification of infections, added to the action of superdiffusers, could explain why 10% of those who are positive for the SarsCoV2 virus are responsible for 80% of infections. It is the so-called ‘over-dispersion’ phenomenon, already observed in other diseases such as influenza and measles, so most of those infected do not transmit the virus significantly, so it is necessary to reach a good number of cases to let the epidemic break out. in an obvious way.
Last Updated: Thursday, October 22, 2020, 20:06
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