NurPhotoLONDON - Having herd immunity to the highly infectious delta variant of the virus with Covid-19 vaccines is "not possible," according to a leading epidemiologist. Experts agree that such an objective where total immunity is achieved and the spread of disease is stopped is unlikely for several reasons. The Oxford Vaccine Group's head Professor Andrew Pollard said Tuesday that Covid vaccines didn't stop the spread of virus, with vaccinated individuals still able transmit the virus. This made it "mythical" to achieve herd immunity. "I think we are in a situation here with this current variant (the delta variant) where herd immunity is not a possibility because it still infects vaccinated individuals," Pollard, one of the lead researchers in the creation of the AstraZeneca-University of Oxford vaccine, said. That does not mean that everyone who isn't vaccinated will get the virus. It might not be next month, next year or this month but they will get the virus at some point and there is no way to stop it. Continue reading: Even though they are fully vaccinated, Covid is still spreading to people who have not been vaccinated. Experts explain the reasonsWhat is herd immunity?Simply put, herd immunity refers to the belief that vaccination can provide high levels of immunity against a virus. This is preferable because vaccines are overwhelmingly effective in creating immunity and do not cause illness or other adverse health consequences, unlike natural infection. Both vaccination and natural infection provide immunity against future infections. If enough people are immune, this can lead to lower rates of infection or other diseases in the community. A virus that has less chance of spreading and infecting others can be controlled or eliminated. Herd immunity protects those who have not been vaccinated, whether they choose to or are unable to be immunized at the appropriate time. Mass vaccinations have resulted in deadly contagious diseases like polio, tuberculosis, and measles being largely eliminated or greatly reduced by vaccination programs and herd immunity.Pollard pointed out on Tuesday that Covid and the current, more virulent, delta variant of Covid were different. "The problem is that this virus [is] not measles. According to Pollard, 95% of measles-infected people would have been vaccinated. The virus could not be transmitted in the population if that happened. He spoke out before the All-Party Parliamentary Group for the UK on the coronavirus. Pollard stated that Covid vaccines may slow the spread of virus. This is because infected individuals who have been fully vaccinated appear to shed less virus. It also makes it less likely that new variants will emerge. I suspect the next variant of the virus could be even more effective at spreading among vaccinated people, so it's important to not make a vaccine program based on herd immunity. People who have been fully vaccinated against Covid-19 will be protected from severe infection, hospitalizations and death due to the virus. A new study from the U.K. showed that people who have been twice vaccinated against the coronavirus were three times more likely to be positive than those who had not. Imperial College London conducted the research and found that people who have been fully vaccinated may be less likely to transmit the virus to others than those who are not.Experts urge all people who are not vaccinated to speak up. However, there are concerns in certain countries in Europe and America with young adults refusing to get the vaccine. CNBC's Andrew Freedman, a Cardiff Medical School reader in infectious diseases, said Thursday that he agree with Pollard's assessment that herd immunity is unlikely. He noted that "The delta variant of the disease is highly transmissible, which means that it is unlikely that all people will be vaccinated to achieve herd immunity." "The vaccines provide very effective protection against severe disease/hospitalisation/death but are less effective in preventing infection, mild disease and transmission, especially for the delta variant." Herd immunity is also possible in countries such as the U.K. due to large numbers of unvaccinated children and adolescents. Some of these would be immune to natural infection, but many would not, Freedman said. He said that even without 'herd immunity', the greater the percentage of people who are fully immunized, the lower the chance of infection in the community.Herd immunity problemsA number of countries, including those in Sweden and the U.K. were ready to hope on "herd immunity" as they allowed the virus to spread to their citizens so that natural immunity could develop. However, the U.K. quickly abandoned this approach as they realized how dangerous and destructive Covid could become. With thousands of cases leading to hospitalizations and death, the threat to the health care system was real. It is difficult to achieve herd immunity to Covid due to a variety of factors, such as uneven vaccine rollouts and vaccine hesitancy. New variants of the virus are also threatening to undermine (but not yet destroying) Covid vaccine efficacy. Continue reading: Will herd immunity ever become possible as Covid mutations continue to spread? Experts are still unsure how long Covid immunity lasts. However, there is evidence that the immune system (naturally acquired or vaccinated) weakens over time.Delta Health Center medical workers wait to immunize people at a pop up Covid-19 vaccination clinic in this rural Delta community, Mississippi on April 27, 2021. Spencer Platt | Getty Images
