The number of Covid-19 cases in India has crossed 16 Lakhs and close to 5.5 lakh persons still remain under treatment for the infection, the Union health ministry urged people to follow COVID-appropriate behaviour till a vaccine is developed as the country is far from achieving any herd immunity.
What is herd immunity?
Herd immunity is when a large part of the population of an area is immune to a specific disease. If enough people are resistant to a virus or bacteria, it has nowhere to go. While not every single individual may be immune, the group as a whole has protection.
This is because there are fewer high-risk people overall. The infection rates drop, and the disease peters out. Herd immunity protects at-risk populations. These include babies and those whose immune systems are weak and can’t get resistance on their own.
Why is it difficult to achieve herd immunity in India?
Rajesh Bhushan, Officer on Special Duty in Union health ministry said:
Given the size of India's population, herd immunity cannot be a strategic choice or option but can only be an outcome, and that too at a very high cost as it means lakhs of people would have to be infected, get hospitalised and many would die in the process.
Bhushan said that in India, herd immunity can be achieved through immunisation but that will be in the future.
The march of an infectious disease such as Covid-19 can be halted only when there is a large enough proportion of the population that is immune to it, a threshold known as herd immunity. Besides a vaccine, which is yet to be approved, the only way people become immune is if they have had the disease and recovered.
He also said:
Government has not signed an agreement with any vaccine manufacturing company. There are multiple stakeholders within and outside the government and ministry of health has started actively engaging with such stakeholders. It’s too premature to comment on supply and distribution of vaccines at this stage but whenever it comes it has to be deployed on a much larger scale than the existing vaccines.
World over, there are roughly 25 vaccines in human trial phases including two from India. Three vaccine candidates, one each from US, UK and China are largely regarded as the frontrunners since they are now at advanced stages of experiments among people.
Several countries have entered into commercial deals with the UK candidate’s developer AstraZeneca and the US candidate’s Moderna. Bhusan said:
India is in touch with global multilateral organisations such as GAVI, CEPI, WHO, to see how it can be made accessible for people in India.
GAVI (Gavi-The Vaccine Alliance) and CEPI (Coalition for Epidemic Preparedness Innovations) have partnered with WHO and several of the vaccine developers to help pool resources for the production, acquisition of distribution of any potential Covid-19 vaccine, with fair access being one of the factors that they will keep in mind.
The two Indian vaccine candidates are Bharat Biotech’s Covaxin and Zydus Cadila’s ZyCov-D, both in phase I/II human trials for determining its safety and dosage.