According to scientist Pollard, the virus will not completely stop spreading despite vaccination coverage. Covid could therefore never be eradicated, but the vaccine guarantees high protection from serious diseases and deaths
With the Delta variant of the coronavirus it is impossible to achieve herd immunity because this virus is not like measles. This was stated by the director of the Oxford Vaccine Group, Sir Andrew Pollard, among the researchers who helped develop the vaccine produced by AstraZeneca. If 95 percent of people have been vaccinated against measles, the virus cannot spread to the population. But the Delta variant will still infect people who have been vaccinated. And that means anyone not yet vaccinated will encounter the virus at some point and we have nothing that can completely stop that transmission Pollard reported at a hearing in the UK Parliament.
Although i existing vaccines are very effective in preventing serious illness and death from Covid, do not prevent, albeit in lower percentages, a fully vaccinated person from being infected with the virus that causes Covid-19 (in most cases the symptoms are mild or absent)
Herd immunity
The concept of herd immunity is based on the fact that the vast majority of a population that gains immunity – through vaccination or a previous infection – provides, in turn, a indirect protection from an infectious disease for the unvaccinated and for those who have never been infected before. But with the Delta, reinfections are possible. Data from a recent React study conducted by Imperial College London suggests that fully vaccinated people aged 18 to 64 have a roughly 49% lower risk of getting the infection than unvaccinated people. The results also indicated that fully vaccinated people are about half as likely to test positive after coming into contact with someone who had Covid.
An endemic virus
Pollard’s words coincide with what several scientists have been arguing for some time. What is looming on the horizon is the possibility that the freedom gained thanks to vaccines does not coincide with herd immunity, but with a reduced, albeit effective, mass immunity. Herd immunity can only be achieved with high vaccination rates which in turn depend on the transmission power of a virus. Researchers predict that the virus will tend to circulate for a long time, albeit likely to become a less evil enemy. In a survey of over 100 scientists conducted by the journal Nature in January, nearly 90% said they expect SARS-CoV-2 to become endemic. Endemic viruses continuously circulate in the community, often causing periodic spikes as conditions favor transmission. Examples include norovirus, which causes gastroenteritis, and the myriad viruses in circulation, including four coronaviruses, which cause the common cold.
Could Covid be eradicated?
It seems anyway coronavirus unlikely to be eradicated. So far, only one human disease – the smallpox – it was officially eradicated with cases reduced to zero cases and maintained over the long term without continuous countermeasures. This was possible thanks to a good vaccine and the fact that humans are the only mammals naturally susceptible to infection with the smallpox virus. Conversely, many species are susceptible to SARS-CoV-2, including bats, minks, cats, and gorillas. One could point toelimination of the disease, possible when there are no new cases in a well-defined area for a certain period of time. Some countries have managed to hit the target after long lockdowns and border closures. But extremely strict health measures cannot be maintained for long periods, and the emergence of new variants makes the enterprise difficult to achieve.
Why vaccinating is important
In the absence of herd immunity, the virus will continue to find those who have no protection. This means that people who are not vaccinated – either cannot because their immune systems are compromised, or have allergies to the vaccine ingredients, or are too young – will remain vulnerable. Those who have been vaccinated or recovered from Covid-19 will maintain a certain degree of immunity. Even if these people are still infected, their immune systems will be able to keep the infection under control and, in most cases, the symptoms will be mild or absent. Furthermore, exposure to the virus will further amplify the immune response by refreshing the memory. Some scientists have predicted that, once it reaches the endemic stage, primary exposure to the virus will occur in childhood, when the infection mainly causes mild or no disease. At that point, Covid can be considered very similar to the common cold.
August 11, 2021 (change August 11, 2021 | 14:53)
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