Bergamo example: how much collective immunity costs

US, WASHINGTON (ORDO NEWS) — During the epidemic, authorities from European countries and even the United States came out with a proposal not to repeat the path of China – that is, not to enter quarantine, but to allow the population to calmly recover without violating its usual rhythm of life. Until now, for example, Sweden has taken this position, where every four-thousandth has already died as a result of the coronavirus, although the end of the epidemic is not yet visible there.

Proponents of such an idea rely on the concept of collective immunity (it is also sometimes called group immunity ). According to it, any infectious disease that has covered a significant part of the population should stop spreading as soon as a certain number of residents have been ill with it.

It is believed that the formation of collective immunity for a new coronavirus is possible if a threshold of 60% of the total population is passed. After reaching it, there will be too many people immune to the new disease, and it will become much more difficult to “jump” from carrier to carrier.

The ideal conditions for testing the idea of ​​collective immunity were presented by an epidemic in the city of Bergamo. About a third of its population attended a football match, from where the spread of a new virus in this region of Italy began. Due to such a large crowd of people, the epidemic swept Bergamo very quickly.

Now, Italian researchers have tested the presence of antibodies in Bergmans. According to it, 61.9% of the tested Bergmans (excluding health workers) have antibodies to the new coronavirus, although their concentration varies greatly. Tested 3320 people aged 18 to 64 years (the results are processed so far only 2581). Antibodies appear in patients who have been ill, which means that almost 62% of Bergmans have already transferred a new coronavirus. Previously, it was impossible to identify, since in Italy there is a noticeable shortage of PCR tests.

Interestingly, only 23.2% have antibodies among medical personnel. This is very unusual, because, logically, doctors more often than others have contacted carriers of a new disease, and are considered one of the key risk groups.

Although the population of the province of Bergamo received collective immunity, the price paid for it is quite high. For example, the total population of the city of the same name and the center of the province is less than 122 thousand people. It is difficult to say how many things died in it from Covid-19, because not all the dead were tested. But according to official Italian statistics, from March 1 to April 4, 2020, mortality in Bergamo has doubled. The number of deaths of citizens for this period by 585 exceeded their number for the same period last year.

Thus, almost every two hundredth Bergamets, approximately 0.5% of the population, died only by April 4. For comparison, in epidemics of influenza, mortality is even among those who have been ill below 0.1%. In other words, the new coronavirus has proven itself many times more dangerous than the flu.

The death toll at 0.5% may seem small, but 0.5% of the world’s population is more than 37 million people. That is, if we expect the formation of collective immunity of the entire population of the Earth, then we must be ready for more than 37 million victims – approximately as in the Second World War. For the United States, 0.5% of the population is more than 1.6 million dead, and for Russia – more than 0.7 million. Apparently, not all countries of the world will be ready for such losses for the sake of acquiring collective immunity.

The Italians who conducted the tests complement the picture, recalling that today it is not known how long the patient has remained immune to the new disease. Previously, Naked Science talked about another study, according to which 30% of newly ill people have too low antibody levels to avoid reinfection. In other words, every fourth person who is ill actually has no immunity. If this assessment is correct, but even in Bergamo it can be difficult to talk about the formation of collective immunity.

The events in Bergamo are extremely significant for the whole world also because from May 4, 2020 there should be removed quarantine restrictions. This city is the center of the province of the same name, with a population of one million. It is believed that in all during the epidemic, five thousand people died. If, after lifting the restrictions, a new wave of the epidemic does not break out there, it will be possible to consider that regions with such a proportion of those who are ill are really safe from new outbreaks of the disease.


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