The start of the new year is all set to augur well. Early 2021 is likely to see Indian companies (the likes of Serum Institute of India and Bharat Biotech) approaching the Indian drug regulator with data to seek emergency use authorisation for their vaccines. That is permission to vaccinate the high-risk category people, who are exposed the most and need immediate protection.
However, riding on the first wave of vaccines is a weight lot more than a hope to overcome the pandemic. They will also be the most-watched vaccines for greater insights into deeper understanding of COVID-19 vaccine itself.
By the time the initial target groups get the vaccine administered – about 30 crore in India – the vaccines used would have by then gone through the necessary scientific and regulatory scrutiny and cleared for their safety and immunogenicity (the ability to trigger the immune response in the body) there may still be a need for caution. “While they would have all cleared the safety and immunogenicity criteria, the data is still based on a limited period of observation with limited data on elderly and children apart from lack of data on sterilising immunity,” says K V Balasubramaniam, an independent consultant and the former managing director of Indian Immunologicals. This, he says, is because although antibodies would develop, the virus may not have been completely cleared from the system. This is why it is prudent to go in a stepwise fashion starting with high-risk groups and eventually reaching the vulnerable groups. Based on these factors, he feels it is crucial that care is taken to administer the vaccine with caution on the high-risk and the vulnerable groups. Also, most of the trials have not been done extensively on people under 18 years old.
As one vaccine-maker, speaking on condition of anonymity explains: “Most of the early vaccine-makers began their clinical trials only five to six months back and therefore by now have data for only for that limited period whereas traditionally vaccines study data for long-term impact over four years before being put to use. That comfort was not possible for early COVID-19 vaccines.”
Why long-term studies matter? It is because, they typically look at aspects of long-term stability, potency, storage, and related potency. These are all being done today based on data for say just about five to six months.
Fortunately, the healthcare workers and other frontline officials, who immediately need protection, also have access to a medical system. Therefore their close monitoring for any unlikely adverse event may be that much easier during the period of emergency use approval.
It all then boils down to the time taken to study a vaccine closely. After all, the pathway for any vaccine development is identical: Testing a vaccine for its stability, effectiveness, safety – first in animals, then on humans in phase 1. This is then followed by the dosage to be decided in phase 2 studies and subsequently the immunogenicity and efficacy in phase 3 studies. Then, there will also be studies on how the product is maintaining its stability at different temperatures. Each of these studies is done for a long duration of time – 2 to 4 years and more – and only then it is easy to ascribe the shelf life for the vaccine. Today, much of this is being compressed in time and based on a limited time period of study.
It is precisely for this reason that most of the vaccines historically have taken 8 to 10 years for development with clinical trials conducted in different age groups and studied over long periods of time, which each kind of study taking 1.5 to 2 years, which is now being compressed into less than one year.
(Views expressed are personal.)