Immunity hurdle for a shot at Covid-19 vaccine

Rapid antibody tests at dedicated Covid-19 vaccination centres to act as screening tool

If you are eager to get a Covid-19 shot at the earliest, breathe easy. You might as well brace for a screening hurdle at dedicated vaccination sites that would identify antibodies, according to sources in the government.

India is likely to take a judicious approach in immunising its humungous population with the much-awaited vaccine for the novel coronavirus.

People who have already developed antibodies against the Sars- COV-2 virus would not be considered for a jab, as the government does not wish to waste the precious vaccine shots.

The dedicated vaccination sites would be equipped with a facility to carry out rapid antibody tests. Therefore, a screening would be essential to prioritise who gets the first doses of the Covid-19 vaccine.

“The sero prevalence rate is 20-30 per cent in metropolitan cities. This implies that these people have already developed antibodies against the virus. Why would a responsible government vaccinate someone who already has antibodies? It is more logical to do a screening through a rapid antibody test before the vaccination is done,” said a senior official, who is working on the mammoth project of a Covid-19 vaccination drive in a country of over 1.3 billion people.

He added that this may be one of many options to prioritise sections of people who are given the vaccine.

Adar Poonawalla, CEO of Serum Institute, the country's largest vaccine maker by doses, recently tweeted his concerns about whether the central government would have ~80,000 crore available over the next one year to buy and distribute the vaccine to everyone in India.

“Why is the need to vaccinate almost the entire population?” asked an official. He added that a sum of ~80,000 crore takes into account vaccinating everyone twice with the Serum Institute vaccine at a cost of $3 per dose.

That, however, may not be the case. Experts felt that antibody screening before vaccinating is a good idea. E Sreekumar, chief scientific officer at the Rajiv Gandhi Centre for Biotechnology, said that the initial availability of vaccine doses may be limited, therefore prioritisation would be essential.

"Eventually, the Covid-19 vaccine should become a part of the universal immunisation programme. This would not only ensure developing herd immunity but would also bring down the prices of the vaccine. By having a certainty of demand, the vaccine makers can produce large volumes, thereby bringing down the prices," he added.

Herd immunity is unlikely to develop before at least 60-70 per cent of the population is vaccinated or has developed antibodies. It is attained when a sizeable section acquires immunity or antibodies against a pathogen that protects the remaining populace that may not have developed immunity. In other words, it breaks the chain of transmission of the pathogen. Herd immunity can be achieved either through vaccine or natural infection, albeit the latter comes at a great human cost.

Besides assessing the augmentation requirements for vaccine cold chain and vaccinators, the Centre is also collating data from states in standard templates on frontline healthcare workers, people with co-morbidities and those above 60 years of age, said a source.

This database would also help the Centre prioritise the vaccine administration.

Bernstein analysts pointed out in a recent report that the Indian government is likely to procure 680 million doses. This will imply a spending of $1.9 billion. If it chose to vaccinate the entire population, the government would need to set aside $6 billion ($1.3 billion to vaccinate 60 per cent for herd immunity, and considering two doses per individual at $3 per dose).

Bernstein analysts estimate that the volumes will be split 55:45 between the government channel and the private market.

Bernstein analysts pointed out in a recent report that the Indian government is likely to procure 680 million doses. This will imply a spending of $1.9 billion