Trust DCGI to ask for enough data before vaccine approval: Gagandeep Kang

Having achieved the first goal of seeing whether the vaccines work, we can be more ambitious and design studies to assess whether and how much they reduce transmission, says Kang

Even as leading pharmaceutical companies are seeking authorisation to roll out their coronavirus vaccines in India, the regulator should not give its approval without first obtaining enough data, suggests Gagandeep Kang, a professor at the Wellcome Trust Research Laboratory of Christian Medical College, Vellore, and one of India's leading medical scientists. “Pfizer has done no trials in India, and Serum has not completed its immunogenicity study,” she says in an emailed interview with Akash Podishetty. Edited excerpts:

A Lancet study shows that the Oxford vaccine's ability to prevent transmission is limited. Even in Pfizer's case, we still don't know of its efficacy in stopping transmission. What might these grey areas mean for containing the outbreak?

Right now we know that the vaccines are preventing people from getting sick and that is the primary and most important outcome in the initial clinical trials. Having achieved the first goal of seeing whether the vaccines work, we can be more ambitious and design studies to assess whether and how much they decrease transmission. If we want to look at decreased transmission efficiently, the design of the study could be different. Instead of an individually randomised trial (where each person has an equal chance of being in a vaccine or comparator/placebo), we could look at a cluster randomised trial design, where all groups receive vaccine or comparator/placebo and the effect on both individuals and the cluster can be studied.

Pfizer and Serum have applied for emergency-use authorisation in India. Are we fast-tracking the process?

Pfizer has done no trials in India, and Serum has not completed its immunogenicity study to investigate the presence of an immune response to the virus protein and its clinical impact. I would expect the regulator (the Drugs Controller General of India, or DCGI) to want enough data before any acceleration of approval.

Given all the logistical and supply issues. What should be the government's strategy?

The government has done well in its planning, anticipating problems and developing strategies, but the ultimate proof of the preparation will be when vaccines are actually rolled out. I am particularly concerned about the priority groups that come after the groups listed by occupation (healthcare workers, essential workers, etc) — that is, the elderly and those with co-morbidities — since we have no experience with adult campaigns, and that too in phases. Communication is critical. We are seeing a decline in wearing masks, and crowding despite the government's constant messaging. What is an effective communication strategy for these? Unlike the US, we do not have organised resistance to masks. For vaccines, all parts of the world have seen an increase in anti-vaxxers, and they are much more effective communicators than health authorities.

Do we need to vaccinate the whole country to halt the pandemic? What is the potential threshold?

No, we do not need to vaccinate the whole country to slow the spread of the virus. But whom would you leave out, and will the choices be justified? Theoretically, anywhere from 50 per cent to 80 per cent of people may need to be inoculated to stop the spread, depending on whether all other inventions are expected to decrease or stop or not.

Vaccines differ in their degrees of efficacy and side effects in various age groups. Is a mechanism of different vaccines for different age groups a possibility?

It is certainly possible – we already do this for chicken pox in children and zoster in adults. The virus is the same but vaccine formulations different; that’s because older people need a stronger vaccine. At the moment, the data seem to indicate that the elderly might respond slightly less well. But still, enough protection is being seen to make one consider these vaccines good for the elderly.

Many are worried about how long the vaccine immunity would last. What do we know so far?

For natural immunity, studies suggest at least six months among those infected, possibly even longer. The short answer is that we cannot yet draw a full conclusion on vaccine immunity based on what is available. The period should be at least as long as infection-induced immunity. We shall have to wait and see.

Does natural immunity offer better protection than a vaccine?

Natural infection is more variable than vaccination. We know this from the fact that 10-15 per cent people with asymptomatic or mild infections do not make detectable antibodies, while practically everybody who receives a vaccine makes a good immune response. We will just have to track people with infections and those who got the vaccine and keep looking at their immune responses and whether they get infected. These are difficult studies to do, but essential to understand immune responses and protection.

Public trust in vaccines is an important part of the immunisation drive. How do we tackle vaccine hesitancy?

Listening and educating (are necessary). If people have beliefs that are scientifically not valid, it is our responsibility to listen to them and understand the basis of those beliefs and then offer accurate information.