Calculated the total weight of all SarsCoV2 virus particles present in the world: it ranges from a minimum of 100 grams to a maximum of 10 kilograms, based on the number of positive people at a given moment of the pandemic.
The estimate, useful for quantifying the rate of occurrence of new variants, is published in the journal of the American Academy of Sciences (PNAS) by the Israeli Weizmann Institute for Sciences.
Starting from studies conducted on macaques, the researchers calculated that every person at the height of the Covid-19 infection should 'harbor' between 1 and 100 billion viral particles.
Given the diameter of the virus, each viral particle should weigh approximately one femtogram, that is, one millionth of a billionth of a gram. Multiplying the mass by the number of particles present in the human body, it is estimated that each person at the peak of the infection carries up to 0.1 milligrams of the virus. If we think that the number of positives globally can fluctuate between 1 and 10 million, this means that the SarsCoV2 viruses weigh altogether between 100 grams and 10 kilograms.
These numbers allow us to better understand what happens in the body during infection, for example how many human cells are infected and how the number of viral particles produced in the body relates to the speed of evolution of the virus.
In fact, researchers have tried to calculate how many mutations the virus can accumulate, on average, during the infection of a single person and in the population. They thus discovered that in the single patient the virus can accumulate from 0.1 to 1 mutation throughout the genome: considering that 4-5 days pass between one case of infection and the next, the virus can acquire about three mutations per month: a figure in line with the evolution rate recorded so far. However, it must be considered that the number of viral particles can vary from one person to another even by 5-6 orders of magnitude, which means that some individuals can have a number of viral particles that is millions of times higher than others.