Delta variant makes collective immunity against Covid ‘mythical’ | Coronavirus



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Achieving collective immunity is “not a possibility” with the current Delta variant, the head of the Oxford Vaccine Group said.

Testifying to MPs on Tuesday, Professor Sir Andrew Pollard said that the fact that vaccines do not stop the spread of Covid meant that reaching the overall immunity threshold in the population was “mythical”.

“The problem with this virus is [it is] not measles. If 95% of people have been vaccinated against measles, the virus cannot be transmitted in the population, ”he told the all-party parliamentary group (APPG) on the coronavirus.

“The Delta variant will still infect people who have been vaccinated. And that means anyone who is still not vaccinated at some point will encounter the virus … and we have nothing that will. [completely] stop this transmission.

While existing vaccines are very effective in preventing serious illness and death from Covid, they do not prevent a fully vaccinated person from being infected with the virus that causes Covid-19.

The concept of herd or population immunity is based on the fact that a large majority of a population acquires immunity – either through vaccination or through previous infection – which, in turn, provides indirect protection against disease. infectious to unvaccinated people and to those who have never been infected before.

Data from a recent React study conducted by Imperial College London suggests that fully vaccinated people between the ages of 18 and 64 are about 49% less likely to be infected compared to unvaccinated people. The results also indicated that people who were fully vaccinated were about three times less likely to test positive after coming into contact with someone with Covid (3.84% vs. 7.23%).

About 75% of all UK adults have now received their two jabs.

Health Secretary Sajid Javid said on Tuesday that plans were in place to start offering Covid booster injections to the UK’s most vulnerable groups from next month. He said the flu shot would be offered at the same time.

But Pollard – who chairs the Joint Committee on Vaccination and Immunization (JCVI) but is not specifically a member of the Covid JCVI committee – wondered if any reminders would be needed.

“The time we would need to increase is if we see evidence that there has been an increase in hospitalizations – or the next step after that, which would be people dying – among those who are vaccinated. is not something that we are seeing right now, ”he said.

Even if the antibody levels induced by the vaccine were to decrease, our immune system would likely remember the vaccination for decades and provide a degree of protection if exposed to the virus, he said. “So there is no reason to panic right now. We don’t see a problem with a revolutionary serious disease.

The question of whether or not to vaccinate those under 16, as countries like the United States, Ireland and Israel have done, has also sparked a scientific debate in the United Kingdom.

The JCVI recommended that only vulnerable children aged 12 to 15 be vaccinated or those living with adults at risk. Some critics have said that rich countries with high immunization coverage for adults, such as the UK, should not rack up doses for children but should give those doses to poor countries, many of which have barely vaccinated their populations. more at risk.

But Professor Devi Sridhar, president of global public health at the University of Edinburgh, pointed out that the only vaccine licensed for use in children aged 12 to 15 in the UK was the Pfizer / BioNTech vaccine.

“I think the real problem is actually not to vaccinate the children against the world – it’s what we do with the boosters that is being discussed in the rich countries, because these are the doses that could be sent to. abroad, ”she said.

“Fortunately… we have a very effective vaccine in AstraZeneca that can be used for the world, but that will not solve the problem for our children here.”

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