Saturday , June 12 2021

# several billion particles of the virus in the body of an infected person

Have you ever wondered how many viral particles sit in the body of a person infected with a coronavirus? Scientists have completed mathematics.

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Israeli and American researchers have tried to calculate the number of viruses present in the body of a person infected with coronavirus SARS-KOV-2. Obviously, they did not count them one by one, but with some math they were able to get a reliable estimate. They share their result only at the moment in publication transferred by MedRxiv.

The first calculation refers to the total number of viral particles present in the body, whether they are viable or not. To do this, they used data published in a study that estimates the number of copies ofARN per gram of tissue in various organs (lungs, trachea and bronchi, tonsils and lymph nodes, digestive system) in macaque rhésus.

## Up to one hundred billion virions in the body of an infected person

To relate this to the human being, they multiply by mass of each organ. For example: there are between 106 and 108 copies per gram of lungs in rhesus macaque. Human lungs weigh approximately 1 kilogram, at donc 109 and 1011 RNA copies in the lungs of an infected person.

This figure includes both viral particles infectious and those that are not. To realize the number of viral particles that are contagious, the researchers conducted the same thinking, but taking into account TCID50 allowing the titer or concentration of infectious viruses to be determined. In the lungs of rhesus macaques, it is estimated to be 102 to 104 per gram of tissue. Multiplying by the mass of the human lungs, we get 105 to 107 infectious viral particles in the lungs.

The researchers also presented some rather surprising data: if we measure all the virions present in the body of an infected person, the scale will be displayed from 1 to 100 µg. Compared to the number of infected people in the world, the resulting figure shows between 0.1 and 1 kg coronavirus !

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