As cases of coronavirus disease (Covid-19) exceed 30 million worldwide, the appeal of herd immunity as an end to the pandemic becomes increasingly persuasive. However, some countries, including India, have recently reconfirmed reinfection through genome sequencing to show that the second infection was caused by the genetically distinct Sars-CoV-2 virus, which has made it dependent on “a major epidemic “In the words of UK pandemic advisor Graham Medley, to end the public health emergency is not only funny but also very stupid.
Herd immunity is used to describe the indirect protection conferred on a population in which the majority of people have natural or acquired immunity to infection. This is possible because a large part of the population is infected or vaccinated. Vaccines have made once-common diseases, such as polio, measles, mumps, and chickenpox, very rare today because the few unvaccinated people who become infected cannot infect the vaccinated population, which stops the spread of the disease.
In an interview with HT this week, Bill Gates explained why the herd immunity strategy won’t work. “Letting people get sick until most are immune and the disease no longer spreads easily will cause millions of deaths. The second (issue that is not addressed) is that herd immunity is always temporary, because children are born without immunity, and eventually there will be enough susceptible people that the disease can easily begin to spread again, ”said Gates, co-chair of The Bill. And Melinda Gates Foundation.
“There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection,” according to the World Health Organization. “We are nowhere near the levels of immunity needed to stop the transmission of this disease. We have to focus on what we can do now to suppress transmission and not live in the hope that herd immunity will be our salvation, ”said Dr. Michael Ryan, executive director of the WHO Health Emergencies Program, in August.
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According to an article on ‘A History of Herd Immunity’ in The Lancet on September 19, researchers at the Harvard School of Public Health and the Massachusetts Institute of Technology in the US said the phrase was used for the first time. by American vet George Potter in the Journal. of the American Veterinary Medical Association in 1916, on an epidemic of miscarriage in cattle and sheep, to describe how retaining immune cows instead of slaughtering them can save the herd.
In July 1919, bacteriologist WWC Topley described the experimental epidemics he created in groups of mice to show that unless there was a constant influx of susceptible mice, the increasing prevalence of immune animals would end an epidemic. In 1922, Topley suggested a parallel between the outbreaks in mice and children, saying: “Such a similarity seems to exist in the case of epidemic diseases affecting school-age children.”
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Vaccines refocused attention on herd or population immunity in the 1960s and 1970s, when public health specialists worked to achieve sufficient levels of vaccine coverage to stop disease transmission and, in the case of smallpox and polio, eradicate disease.
Only a vaccine can end the Covid-19 pandemic. “A vaccine is essential. It will save lives now and protect future generations from experiencing this experience again, ”Gates said.
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