Herd immunity takes place when a large portion of the population has immunity against disease or infection. It makes the virus or bacteria unable to spread further. In such a case, people who do not have protection against the disease as well are indirectly immune. As per the data, the expected threshold for herd immunity for the COVID19 is nearly 65 to 70 percent. Experts have said that though it is too early to conclude, Israel might be close to reaching herd immunity considering if cases of COVID19 continue to reduce in all age groups. More than 5.3 million people have been immunized against the SARS-CoV-2 virus so far in the country. Nearly 830000 people might have some natural immunity as they have been tested positive for the virus during the pandemic. Collectively, it means that around 68 percent of people in Israel might have antibodies in their bloodstream to fight off the virus.
Professor Eyal Leshem, who is the director of the Sheba Medical Center, has said that herd immunity might be a possible reason for the fact that cases have been falling even when more restrictions have been lifted in the country. He has said that the nation has been seeing a constant decline in the number of cases even after returning to near normalcy. Dr. Leshem has said that it proves that even if a person is infected and roaming around, people who are in close proximity to the infected person will not contract the virus. In Israel, COVID19 cases have seen a decline among all age groups, even among children below 16 years, who have not been vaccinated yet.
Health experts believe that a person who has contracted the SARS-CoV-2 virus can infect three to four other people on average if there are no restrictions in place. If three people are infected with the virus, then, practically, once two-thirds of the population has some protection against the virus, an infected person can only spread the virus to only one other person on average. However, this is sufficient for the virus to spread but not enough for it to grow further. Health experts say it might be simple, but reality can be a little different. The vaccines are not completely effective.
They might prevent people from falling ill with the virus but they do not prevent infection completely in all people. It means that some people who have been vaccinated might be able to spread the virus. Not everyone who has been infected with the virus in the past will have strong and long-term immunity against the disease, given the situation where new strains of COVID19 are more contagious. It proves that there is a need to vaccinate more and more people before reaching herd immunity. Experts have claimed that authorities need to focus on maintaining constant low levels of COVID19 infections.
Dr. Sarah Pitt, who is a virologist at the University of Brighton, has said that authorities need to be more cautious before declaring that herd immunity has been achieved. She has said that the UK is way too far from reaching herd immunity against COVID19. As per the report, only half of the population in the UK has been identified with protective antibodies against the virus through prior infection or vaccination. However, the country has started to see the effects of vaccination on the number of hospitalization and deaths due to the disease. The UK has witnessed huge declines in the number of COVID19 cases in the majority of vaccinated age groups. Health experts have said that there have been huge reductions in cases among younger people as well. It means that vaccines might be able to prevent some spread of the virus.
Professor Eyal Leshem has said that if some strains of the virus show resistance to vaccines in the future, it might be possible that people who are identified with less immunity might fall below the herd immunity threshold. However, it can be handled with tweaked vaccines such as annual flu shots. It shows that even if Israel has achieved herd immunity and if the UK follows the suit, it might not be a permanent thing. This is what has happened with measles in recent years. Authorities have thought that the measles virus has been eradicated from the UK but the World Health Organization (WHO) has retracted the measles-free status of the country in 2019 after a significant increase in the number of measles cases due to less vaccine coverage.