No need for imposition of fresh lockdowns on district or state level to contain the spread of COVID-19, says IIT professor M Vidyasagar.
Experts are living no stone unturned to find a cure for COVID-19, the infectious viral disease which has claimed hundreds of thousands of people worldwide. While scientists are racing against time to develop a vaccine or cure for the disease, some experts are strongly advocating a strategy known as herd immunity as a potential weapon to fight the novel coronavirus. The plan is to expose a huge percentage of the population to the virus, allowing them to get infected by it first and then develop immunity against it. This will break the chain of transmission and help reduce the infection rates. The experts believe that herd strategy can really work in India as the country has a high proportion of younger population, who have lower risk of death and hospitalization risk due to COVID-19. For the herd immunity to be effective, it is estimated that around 60 per cent of the population need to become resistant to the novel coronavirus.
Now, a new study has suggested that herd immunity can be achieved with fewer people than it was estimated. The research, conducted by mathematicians from the University of Nottingham and University of Stockholm, was published in the journal Science on Wednesday. According to their model, the threshold percentage of population who need to be infected for the chain of transmission to be broken was 43% and not 60%, as estimated earlier.
The 43% figure should not be interpreted literally as an exact value and instead be seen as a study of how population differences affect herd immunity, the scientists warned.
Also, the researchers cautioned that the humanitarian and medical costs of taking the route continue to remain high, especially in India.
The scientists also came out two important findings about herd immunity. One is that activity level mattered more than age differences. They found that individuals who were more socially active were more likely to get infected and spread the virus.
Another finding was that herd immunity can be achieved in two ways: by vaccinating enough number of people or if enough people are infected and develop immunity against the disease. According to the researchers, the herd immunity level is lower when immunity is caused by disease spreading than when immunity comes from vaccination.
The debate over the herd immunity has been going on since the last six months. Countries such as the United Kingdom has already discarded the strategy after studies predicted millions of deaths.
Some experts argue that even if the model's prediction was correct, there's no seroprevalence study suggesting that any country was close to achieving herd immunity.
Citing a recent study that found that levels of an antibody in recovered Covid-19 patients fell sharply in 2-3 months after infection, a few other experts opined that even if herd immunity was achieved, there is no guarantee that antibody levels will stay the same.
Meanwhile, researchers at the Princeton University and the Center for Disease Dynamics, Economics and Policy (CDDEP) a public health advocacy group based in New Delhi and Washington, are pretty sure that herd strategy will work in India, where young people constitute the majority of the population. They believe that if India exposes its people to the COVID-19 virus in a controlled way, then by November, 60 per cent of its population may become immune to the viral infection.
