Scientists Fear that Herd Immunity will be Impossible with Delta Variants.

COVID-19 vaccination rate is rising gradually across the globe and people are now asking, as to how much longer will this pandemic last? It is common knowledge that once enough people will gain immunity to SARS-CoV-2 to prevent further transmission, (also known as ‘herd immunity threshold’) things will become clear. An important element of herd immunity is the high vaccination rate. The sooner everyone gets the vaccine, the quicker the herd immunity threshold will be achieved and society can return to normal.

But as the Corona virus is getting evolved and different variants are showing up, the dream of achieving herd immunity isn’t going to turn into a reality any soon. Sir Andrew Pollard, head of the Oxford Vaccine Group, and a professor of pediatric infection and immunity at the University of Oxford said during a Parliamentary meeting in the UK that achieving herd immunity is “not a possibility” now that the Delta variant is circulating.

Prof. Pollard, who is also the chair of the Joint Committee on Vaccination and Immunisation, which advises the United Kingdom government, was giving evidence to Members of the House of Commons of the U.K. Parliament.

His comments follow the preprint publication of the latest data from the Real-time Assessment of Community Transmission 1 (REACT 1) study, which suggests that the COVID-19 vaccines are only 49% effective against the Delta variant of SARS-CoV-2.

He went on to say, “We know very clearly with coronavirus that this current variant, the Delta variant, will still infect people who have been vaccinated, and that does mean that anyone who’s still unvaccinated, at some point, will meet the virus.” He also added that if the new variant of coronavirus will be more transmissible in vaccinated individuals, then herd immunity will never be reached.

But the good news for those who are vaccinated is that, if they ever get infected by the Delta variant then the disease will be much milder which has a higher rate of recovery, in comparison with those who aren’t vaccinated.

Prof. Sheena Cruickshank, of the Division of Infection, Immunity & Respiratory Medicine at the University of Manchester, U.K., said that “Herd immunity usually refers to the proportion of a population that needs to be immune to an infection to protect those who cannot be immune, and vaccination is the way to achieve this, as it is safest.” She further elaborated that, “For true herd immunity, you need a good level of vaccination and evidence of sterile immunity, [that is,] you cannot contract the infection to which you have been vaccinated.” This isn’t possible with Coronavirus as the vaccinated people can still potentially be infected and transmit the virus, though the rate of transmission is much lower for vaccinated folks than unvaccinated ones. Many experts believe that herd immunity with COVID-19 is still possible, even with a high infection rate. Those who are fully vaccinated, still hold the risk of disease transmission. A promising example is Israel that is soon to reach its herd immunity goal with almost 80% vaccinated adults.

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