Covid-19 vaccine for high-risk kids should be prioritised

Chandrakant Lahariya
Public Health Expert

IN India, indigenously developed plasmid DNA- based Covid-19 vaccine, Zydus Cadila’s ZyCoV-D was given emergency use authorisation (EUA) for the 12-17 year age-group (as well as adults), in August 2021. It became the country’s first Covid-19 vaccine licensed for the children. Then, on October 12, the Subject Expert Committee (SEC) of the Central Drug Standard Control Organisation (CDSCO) recommended the approval of Bharat Biotech’s Covaxin for the 2-17 year age-group. As the next step, it has to be cleared by the Drugs Controller General of India (DCGI). In addition, two other vaccines — Covovax (2-17 years; Serum Institute of India) and Corbevax (5-17 years; Biological E Ltd) — are undergoing clinical trials in children.

Soon after the EUA for ZyCoV-D, there was excitement and interest among parents that children are about to and should get vaccinated. However, nearly two months since then, the vaccine is yet to be rolled out for any age-group. With the SEC giving clearance to Covaxin, the interest and hope of the parents about the vaccination of children starting soon, have been revived. However, the moot point is: Do children really need the Covid-19 vaccine? Also, it can be asked that if the licensing of a vaccine does not mean starting the vaccination of that age-group, what is the purpose of licensing? Let’s delve into both issues.

The SARS-CoV-2 infections occur in all age- groups, and therefore, the vaccine researchers and manufacturers conducting clinical trials in children, is understandable. Then, once the trials are completed, the findings and data are submitted to the regulatory authorities — the DCGI in India — for approval. For vaccines before the Covid-19 pandemic, the approval would mean availability in the private market. However, in case of Covid-19 vaccines, since it has been an expedited process of the EUA with limited and at times no follow-up data, the vaccines are not made available in the market. Then, the EUA by the regulatory body is a process completely delinked from the programmatic roll-out of vaccines.

The decision on whether (or not), when and who should be administered the Covid-19 vaccines under the government programme in India is recommended by the National Technical Advisory Group on Immunisation (NTAGI) and needs to be endorsed by the National Expert Group on Covid-19 Vaccination (NEGVAC). One can recall that even after the EUA of two Covid-19 vaccines for adults (18 year onwards), by the DCGI in January 2021, the vaccination of all adults did not start immediately. The vaccines were rolled out — as per the recommendations of NTAGI and NEGVAC — in a phased manner — first the health staff and frontline workers, then the elderly and 45 to 59 year old with co-morbidities and so on.

How the NTAGI arrives on recommendations on whether to vaccinate a specific age-group or the other? The criteria are globally agreed upon and have been detailed in India’s National Vaccine Policy of 2011. In the context of Covid-19 vaccination of children, two considerations — the risk and benefit of vaccination by age-groups and optimising the available supply (prioritisation) are very relevant.

The currently available Covid-19 vaccines in India are not proven to prevent the transmission. However, they reduce the risk of serious illness and death in a vaccinated individual. The epidemiological evidence from the last 18 months of pandemic indicates that children do get infected at the rate nearly similar to the adults (as also reported in the fourth nationwide sero-survey in India). However, the risk of moderate to severe disease is low. Therefore, the benefit of vaccinating children is lower than vaccinating the adults. Then, though the Covid-19 vaccines have been given EUA after examining their safety profile in clinical trials, the trials on children in India, however, had been and are being done on 500 to 1,500 children only. Such sample size is sufficient to provide an indication on safety in the context of common adverse events and immunogenicity of vaccines; however, not enough to identify any adverse event which may occur among one in more than 1,500 vaccinees.

It is scientifically known that the rate of vaccine adverse events in general and Covid-19 vaccines specifically are inversely proportional to the age. A few rare adverse events such as viral myocarditis (with mRNA-based vaccines) and blood clots (with viral-vectored vaccines) are more common in younger age-groups. Therefore, the risk in Covid-19 vaccination is greater in children than in adults. The clinical trial of Oxford-AstraZeneca vaccine (AZD1222) in 5-17 years had to be halted — due to rare blood clot events, in trial participants — and is yet to resume. This vaccine is being administered to millions of adults in many countries. In short, the benefit of Covid-19 vaccination in children is lower and the risk greater (than in adults). It is because of this risk-and-benefit analysis that only a few countries have started vaccinating children and in spite of having access to licensed vaccines and sufficient supply, have prioritised the vaccination of high risk sub-group in children.

Both ZyCoV-D and Covaxin have not been used in children outside the clinical trials. Therefore, it will be logical that India also prioritises high-risk children only. A decision on vaccinating healthy children should be deferred till complete data from the clinical trials is available and also factoring in additional vaccine adverse event data from the high-risk children, which will accrue over a period of time. Covid-19 vaccination of children should not be influenced by political expediency or any external urgency and has to be exclusively guided by and based upon a calm assessment of the data, evidence and science.