A biomathematics researcher has made an estimate of the amount of virus circulating in the world. According to him, this represents the equivalent of a can of soda.
- The diameter of a coronavirus is a thousand times smaller than a human hair
- According to an estimate of the amount of virus in circulation, their size leads to the fact that they could be contained in a can of soda
A barely filled soda can: this is what the amount of coronavirus circulating on the planet is comparable to. Christian Yates, a lecturer in biomathematics at the University of Bath in the UK, made the startling estimate. He explains his approach on the site Tea Conversation. “Even if we are going to set the course towards an approximation based on the most “reasonable” assumptions, I readily admit that this one is, in certain aspects, largely perfectible“, says the researcher.
Infinitely small virus particles
To arrive at this estimate, he first relied on the number of people infected each day. “We will assume that humans are the most significant viral reservoir, although this is an approximation since the virus is also present in some animals.“, he underlines. Half a million people test positive every day, but we must add asymptomatic or unscreened people. According to epidemiological modeling, around three million people are infected every day. According to the moment, they carry more or less virus: this is the concept of viral load. The peak is reached around the 6th day after infection. Moreover, a previous research carried out on monkeys estimated that there is has between 1 and 100 billion particles of SARS-CoV-2 in our body at the time of the peak. Christian Yates has chosen to work from the figure of 10 billion, representing the geometric mean. Taking into account this figure and the evolutions of the viral load, the researcher estimated that there would be two hundred million billion viral particles in the world. For comparison, this quantity corresponds approximately to all the grains of sand present on the planet. O a the Covid-19 is a virus much smaller than a grain of sand: the particles which compose it measure between 80 and 120 nanometers in diameter, knowing that a nanometer is equivalent to one billionth of a meter. “To get an idea, the radius of SARS-CoV-2 (50 nm, based on a diameter of 100 nm) is about 1,000 times thinner than a human hair.“, he underlines.
A volume of about 160 ml
Once he was able to estimate the amount of virus present on the planet, the British scientist quantified its volume. Knowing that SARS-CoV-2 is spherical, the volume of a particle would be 523,000 nanometers3. “By multiplying this tiny volume by the very large number of particles that we calculated above, and by converting the result into a more evocative unit of volumes, such as the milliliter, we obtain 120 ml“, concludes Christian Yates. As these particles are spherical, there is necessarily a space between them, like between oranges that we would try to stack. For the scientist, the total volume occupied by these particles represents approximately 160 ml, i.e. less than a filled soda can.”It is amazing to think that the cause of all this loss of life, all these problems, all these disruptions and difficulties that we have been experiencing for a year could be stored in such a small bottle, he laments. Which would then contain one of the most infectious beverages in history.” According to his calculations, if he had taken into account the high estimates for the diameter of the particles, the volume would remain less than 33 cl, or the volume of a can of soda. A surprising perspective given the devastating consequences of the epidemic around the world.
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