Comment

Don’t doubt Indian vaccines

Covaxin vaccine being administrated at Rajiv Gandhi Govt. General Hospital on Sunday.   | Photo Credit: R. Ragu

Several people have questioned the emergency approval given to the indigenously developed COVID-19 vaccine. They have demanded efficacy data and cast aspersions on the regulatory machinery. Such views will only increase vaccine hesitancy.

It is not the case that the vaccine developed indigenously is being pushed by vested interests, while the international vaccines are great. Questions have been raised about the Moderna and Pfizer vaccines too, which have reported more than 90% efficacy. As Peter Doshi wrote in The BMJ, questions have been raised about the exclusion of individuals from the efficacy analysis for ‘important protocol deviations’; the higher rate of medication in the vaccine arm to prevent side-effects due to reactogenicity; the processes of the primary event adjudication committees, comprising the companies’ own employees; vaccine efficacy in those who already had COVID-19; the non-availability of raw trial data; and so on.

Efficacy assessment

Efficacy would actually mean testing, say, 10,000 individuals who have been given the vaccine versus an equivalent number not given the vaccine in terms of the number who get the infection. Can these vaccines prevent transmission? We may have to wait at least six months to get meaningful results. Efficacy would reflect in the rate of hospitalisation, ICU cases and deaths. With a declining level of infection, perhaps the virus is weakening in India on its own, as is the case with most pathogens. This makes efficacy assessment of a vaccine very difficult.

The question of antibody-dependent enhancement, a phenomenon in which virus-specific antibodies enhance the severity of the virus, and in some cases the replication of the virus, has been put on the backburner with experts suggesting it may not be a major issue. It depends on vaccine design and it is not known whether all the candidate vaccines have been tested for this phenomenon.

In the case of the rabies vaccine, efficacy assessment is based on the virus neutralisation capacity of the serum from the vaccinated individual, assessed in terms of international units. It is a surrogate marker for efficacy, since the candidate vaccine cannot be tested in an experimental population that is administered the virus or bitten by rabid dogs, for validation. At this stage, no one can predict whether the COVID-19 vaccine candidates can protect against the circulating mutants. The SARS-CoV-2 virus is both intellectually and medically challenging. But there has been no prevention strategy in history other than vaccination to save lives. Therefore, vaccination of the population is very important for protection against fresh infections and a second wave, although the duration of protection is not known for any vaccine candidate. It is well known that some people take the flu vaccine every year.

The SARS-CoV-2 pandemic has been extraordinary, both in terms of positive and negative developments. The cooperation among the scientific community, industry and regulatory agencies has been truly remarkable in making vaccine development and deployment possible in less than two years, a process that would otherwise take 10-15 years. The future timelines for research and development, product development and expectations will be very different. On the negative side, we have tall claims by political leaders in the West on vaccines, major scientific journals coming under pressure to publish data with poor peer review, vaccine nationalism, etc.

Moving ahead

Given the context of the pandemic, it would be prudent for India to go by safety studies (Phase I and II) and assessment of virus neutralisation assays with the serum. It is also not appropriate to doubt the integrity of the expert committee advising the Drugs Controller General of India (DCGI). The DCGI is not just an individual to be pressured; it follows due process for making an informed decision regarding emergency use, or, as is called in India, approval for restricted use.

It is understandable that limited approval has been given in clinical trial mode, where individuals vaccinated will be monitored regularly. Though no particular vaccine candidate should be favoured, candidates with proven safety studies and efficacy, as assessed based on the virus neutralisation potency of the sera, should be allowed to go ahead. One or two more months into the trial could have given partial data to satisfy interim efficacy assessment, but we will get real data on efficacy only after vaccinating the masses. Eventually, affordability could become an issue. Selective criticism of indigenous efforts will only jeopardise such efforts. India has a huge population to be vaccinated and we need to move ahead.

G. Padmanaban is former Director, Indian Institute of Science, and Senior Science Innovation Advisor, Department of Biotechnology. Email: geepee@alumni.iisc.ac.in

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Printable version | Mar 1, 2021 3:33:41 AM | https://www.thehindu.com/opinion/op-ed/dont-doubt-indian-vaccines/article33603184.ece

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