The Delta variant changed the equation to achieve herd immunity, said vaccine developer Oxford / AstraZeneca.
Speaking at a meeting of the UK Parliament on Tuesday, Sir Andrew Pollard, professor of childhood infection and immunity at the University of Oxford, said achieving herd immunity "is not possible" now that the Delta variant is circulating.
“We clearly know from the example of the coronavirus that this current variant, the Delta variant, still infects people who have been vaccinated, which means that everyone who has not yet been vaccinated will at some point encounter the virus,” he said. Pollard.
Herd immunity is unlikely to ever be achieved, he said, saying the next variant of the new coronavirus would "perhaps be transmitted even better in vaccinated populations."
Vaccinated people can still get the Delta variant
Some experts hoped that herd immunity could be achieved with COVID-19, as was the case with measles, which is also highly infectious.
Many countries have achieved herd immunity against measles by vaccinating 95 percent of the population, such as the United States, where endemic transmission ended in 2000. This is because after being vaccinated against measles, a person cannot transmit the virus.
However, growing evidence suggests that fully vaccinated people can still transmit the virus with the Delta option.
“We have nothing to stop the transmission of the virus to other people,” Pollard said.
Israel is a good example of this: Cases of COVID-19 dropped in the country after nearly 80 percent of the adult population was vaccinated, giving some hope that herd immunity was achieved, but the Delta option has caused another spike in cases since then. diseases, writes the scientific journal ScienceAlert.