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The idea of stopping the spread of the coronavirus by achieving natural herd immunity by letting the virus spread among healthy people is a “dangerous mistake, not supported by any scientific evidence.” It supports a group of 80 researchers in an open letter “Memorandum of John Snow” published in The Lancet magazine. Signatories to the letter include numerous international experts with skills ranging from public health, epidemiology, medicine, pediatrics, sociology, virology, infectious diseases, health systems, psychology, psychiatry, health policy, and mathematics. “Uncontrolled transmission in young people runs the risk of causing a significant spread of the virus with mortality throughout the population ” scientists write. “In addition to the human cost, this would have a disastrous impact on the workforce, sending health systems into a crisis even for routine care. Among other things, defining who is vulnerable is decidedly complex, and in some areas people at risk represent 30% of the population. Prolonged isolation of large sectors of the population is practically impossible and highly immoral.
The problem of reinfections
The approach of achieving herd immunity, they write, is fallacious and costly in terms of human and economic lives, and still would not stop the virus, which would return several times in new recurring waves. Scientists note that there is growing evidence that lPost-infection immunity to Sars-CoV-2 lasts for only a few months after infection., then disappears and the risk of reinfection is not remote. 23 cases have been recorded worldwide, sometimes with better results and sometimes worse than the first time. The analysis was published a few days ago in The Lancet and the scientists concluded that: “Re-infection cases tell us that we cannot rely on immunity acquired through natural infection for herd immunity. This strategy would not only kill a lot of people, it wouldn’t work either. Achieving herd immunity requires safe and effective vaccines and widespread vaccination of the population.».
The controversial American petition
The letter from the 80 scientists comes from an online petition and a document called The Great Barrington signed by a large group of other prominent scientists. Jay Bhattacharya, an epidemiologist and infectious disease expert at Stanford University, where Dr. Scott Atlas, Donald Trump’s scientific advisor, also works. In the letter (married by the White House) Letting the virus run its course among young people and people in good health who are unlikely to develop serious illness is suggested, with the aim of protecting and isolating the most vulnerable.i (by age and clinical status). The ultimate goal is precisely “herd immunity”, which occurs when a sufficient part of the population becomes immune to a disease, either because it has been vaccinated or because it has contracted the virus, is cured and has developed antibodies. In this way, according to the authors, the social and health costs caused by confinement would be avoided.
Criticisms from the scientific community
The position was criticized by the scientific community, which on the one hand highlighted the difficulty (if not impossibility) of Establish a clear separation in society between the different vulnerable groups., on the other hand underlined the rThe young population is also likely to face complications. (in some cases long-term) after contracting the infection. The Director-General of WHO Tedros Adhanom Ghebreyesus, stressed that “herd immunity is achieved by protecting people from the virus, not exposing them. Never in the history of public health has it been used as a strategy to defeat an epidemic. Much less for a pandemic. It is scientifically and ethically problematic.
Because restrictions are needed
Now this latest letter from the 80 scientists adds to the criticisms already expressed in recent days. “It is essential to act decisively and urgently,” the scholars wrote. “Effective measures that suppress and control transmission must be widely implemented and must be supported by financial and social programs that foster community responses and address the inequalities that have been amplified by the pandemic,” they add. “Continued short-term restrictions are likely to be needed to reduce transmission. and review ineffective pandemic response systems to prevent future lockdowns. The purpose of these restrictions – continue – is yesIt effectively suppresses Sars-CoV-2 infections at low levels that allow rapid detection of outbreaks. localized and rapid response through efficient and comprehensive systems to search, test, trace, isolate and provide support so that life can return to near normal without the need for widespread restrictions. The protection of our economies is inextricably linked to the control of Covid-19. We need to protect our workforce and avoid long-term uncertainties. ‘
Infections in relation to immunity.
When talking about herd immunity, it is generally referred to as limit, equal to the percentage of individuals in a given population that must be immune, for the virus to become extinct in that population, assuming that immunity lasts long enough (which, as already written, does not appear to be the case with the new coronavirus) . Considering the contagiousness of Sars-CoV-2, it is estimated that ch if at least 60-70% of the population had been infected, we could benefit from the protection of herd immunity. The new coronavirus is really contagious, but much less than measles, so it is estimated that herd immunity is achieved only if 95% of the population is vaccinated.. How far are we with infections in Italy? It is not very easy to answer. Although in some small countries there are up to 30% HIV positive and health personnel have certainly been more exposed, at this time it is estimated that at the national level 2.5% of the population has been infected (7.5% in Lombardy ). Figures still far from herd immunity that, however, living in a globalized world, should be calculated globally.
October 15, 2020 (modified on October 15, 2020 | 14:06)
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