Dose too far

It will take some time before non-priority groups get the vaccine

PTI01_12_2021_000133B Shot delivery: The first batch of Covishield vaccine reaches the central storage facility at Rajiv Gandhi Super Speciality Hospital, New Delhi | PTI

With its “staggered” procurement of 1.1 crore doses of Serum Institute of India’s Covishield (at Rs200 plus taxes a dose) and 55 lakh doses of Bharat Biotech’s Covaxin (at Rs295 a dose), India has kicked off what is said to be the world’s largest immunisation drive against Covid-19.

In the first phase, three crore health care and frontline workers will be administered two shots of either of the approved vaccines, four weeks apart. While the vaccine launch may signal the beginning of the end of the pandemic, when it comes to public health priorities, the government will have to do a balancing act. One of the challenges is to ensure access and equity in vaccine distribution. Another is about building a strong mechanism to report adverse events.

“Despite all the planning, there will be some hiccups,” said Dr Vineeta Bal, former professor, National Institute of Immunology, Delhi. “For instance, at some places they may be related to cold chains and logistics. At others, a doctor may not be able to reach on time to deal with an adverse event.” The government’s plan of drawing upon the country’s experience and mechanisms of conducting elections may not work. That process does not involve taking informed consent and counselling, both of which are essential in a vaccination drive, she said. “Though vaccines are safe and adverse events rare, it would be crucial to rightly identify any events post immunisation, and be able to provide timely and adequate treatment,” said Bal.

In such a situation, what is bound to help is that the first lot to be vaccinated are health care workers. “The rollout is beginning with this captive population,” said Dr Shahid Jameel, director of Trivedi School of Biosciences, Ashoka University, Haryana. “Among the 30 crore beneficiaries divided into various priority groups, these [three crore] are the most orderly and so, the easier ones to begin with.”

To obtain full licensure, further data on side effects, adverse events and efficacy would need to be gathered and analysed from this lot, before the government can scale up the programme to other high-risk populations. While the government has been training vaccinators, certain gaps remain to be filled. For instance, Dr Balram Bhargava, director general of Indian Council of Medical Research, had said that Bharat Biotech had been asked to generate standard operating procedures for the administration of Covaxin in “clinical trial mode”. Those SOPs have not yet been released.

“Health care workers are more likely to identify and report any adverse events, as they know how to deal with them,” said Dr Jacob John, professor, Christian Medical College, Vellore. “In any vaccination drive, adverse events are bound to happen, but what is crucial to know is their severity. That data has to be transparent. It will allow better decisions on scaling up, and build confidence in the system.”

India’s vaccination drive coincides with a steady decline in active cases. Currently, India has around 2 lakh active cases, and a case fatality rate of 1.4 per cent. In a pandemic, the declining caseload and a high rate of sero-positivity pose unique challenges for vaccine developers and manufacturers. First, evaluating for efficacy in phase 3 trials becomes trickier. In India, there are at least five other vaccine candidates still in the fray. While the Zydus Cadila candidate is beginning phase 3 trials and Sputnik is in phase 2/3 trials, the candidates from Gennova and Biological E may begin phase 2 trials by March, according to health secretary Rajesh Bhushan.

“Once the pandemic slows down and a vaccination drive has begun, the motivation for participants to be part of a trial goes down, and recruitment becomes a challenge,” said Jameel. In phase 3 trials, participants are divided into vaccine versus placebo groups, and subsequently, evaluators wait for a certain number of people to be exposed to infection to judge efficacy. “Now, if the pandemic has slowed down, it will take a longer time to reach that threshold of infections (cumulative number in both the placebo and vaccine groups), and hence, trials take longer,” said Jameel.

The government wants to vaccinate 30 crore people in the priority groups by mid-2021. In the initial months, supply of an adequate number of doses might be a challenge. Though the government has not yet made this distinction in its vaccination strategy, one way of maximising the limited number of doses would be prioritising on the basis of history of exposure to the virus, said Dr Nimesh Gupta, head, immunology, National Institute of Immunology. “We have seen both the durability and the good quality of immunological memory in Covid-19 patients in India. So, individuals who are exposed to this virus and have good antibodies against it, could be in the last slab of receiving a vaccine. We must quickly generate data to see if a single dose immunisation can serve as a ‘booster immunisation’ in such antibody positive individuals,” he said.

As the vaccination drive progresses, the government will need to address the issue of expanding access to vaccines beyond priority groups. For those outside the priority groups, it could take up to a year until vaccines would be available in the open market, said Jameel.

Pertinent issues around demand and supply of the vaccine will be revealed over the next few months. But, in the rush to attend to this, the government would have to be careful that other public health priorities are not compromised. Already, the health ministry has postponed the Polio National Immunisation Day. “In all these months of the pandemic, we may have ramped up our tertiary care infrastructure such as hospitals and quarantine centres, but vaccination is about primary health care,” said Bal. “There, we are still falling short. Compromising on routine immunisation might just mean more cases of diphtheria, TB and meningitis.”