Researchers calculate surprising absolute numbers on the coronavirus. These can even help to recognize patterns.
According to an extrapolation, the mass of all Sars-CoV-2 virus particles currently circulating in humans worldwide is between one hundred grams and ten kilograms. Each infected person carries only about 0.001 to 0.1 milligrams of virus at the peak of their infection – significantly less than the weight of a poppy seed, researchers reportteams from Israel and the USA in the “Proceedings” of the US National Academy of Sciences (“PNAS”).
The explorersinside and researchers see more than just mathematical gimmicks in their work: Knowledge of the absolute numbers could help to better understand the dynamics of the disease and the course of the pandemic. They point out that their calculations are approximate values, since the viral load, for example, can be very different in individual people and fluctuates extremely over the course of the disease.
Up to 100 billion particles at the peak of the infection
The team led by Ron Sender from the Weizmann Institute of Science (Rehovot / Israel) first determined the number of all Sars-CoV-2 virus particles in individual tissues and in a single individual based on previous studies on macaques. They found the highest virus concentration in the lungs; in other tissues such as the nasal mucous membranes, lymph nodes and the throat, the number was significantly lower.
They then converted the information for humans. They determined that between one billion and 100 billion virus particles circulate in an infected person at the peak of the infection. Even with the higher estimate, the number of body cells is more than 100-mal so grosswrite the researchers. Up to three billion virus particles would be formed in the human body during the entire course of the infection. Taking into account the mass of around one femtogram per virus particle, the researchers determined the above figures. One femtogram is equal to 0.000000000000001 grams.
Estimates are designed to help identify new patterns in the pandemic
In further calculations, the researchers determined, among other things, how many mutations occur, what proportion of the body’s cells can be infected by the virus or how many antibodies are required to neutralize the pathogen.
Estimates of the total number and mass of Sars-CoV-2 virus particles in infected individuals made it possible to identify various aspects of the pandemic – from immunology to evolution – connect with each other and recognize new patterns that are not immediately obvious, according to the scientists.