Covid-19 vaccines for very young children

Dr B.J.C.Perera 

MBBS(Cey), DCH(Cey), DCH(Eng), MD(Paed), MRCP(UK), FRCP(Edin), FRCP(Lon), FRCPCH(UK), FSLCPaed, FCCP, Hony FRCPCH(UK), Hony. FCGP(SL) 

Specialist Consultant Paediatrician and Honorary Senior Fellow, Postgraduate Institute of Medicine, University of Colombo, Sri Lanka.

In any immunisation programme against an infective disease, the aim is to vaccinate as many of the susceptible population as possible. That is a fundamental principle in epidemiology. There is absolutely no question in the minds of the experts that in the case of the raging COVID-19 pandemic that is causing havoc right round the globe now, there is universal susceptibility of all humans of all nations, all populations and all social groups of the people of planet earth to this miserable blight. There are no worthwhile differences in the ethnic groups, age categories and socio-economic assemblies in their actual propensity for contracting the disease. The virus will get in and infect anyone anywhere. There are only differences in the severity of the illness and the tendency to die from the disease in certain well-understood categories or age groups of people.

It is a well-recognised fact that the coronavirus disease may be quite asymptomatic in a vast proportion of affected youngsters of all age groups, ranging from very young pre-schoolers to adolescents and even young adults. In another significant though rather small proportion of children and young people, the symptoms are quite mild. Only in a very small minority, perhaps as low as 1 to 2 percent of affected children, is the disease is of such severity as to need intensive treatment. In the United States of America, a proportion varying from 0.01% to 1.9% of all affected children needed hospitalisation. Their death rates in children in different states has varied between zero to about 0.25% of all deaths in all age groups from COVID-19. However, this has varied somewhat in different countries due to individual susceptibilities, coexistent other diseases and of course the ‘variants of concern’ such as the Delta strain, as described by the World Health Organisation (WHO).

With all this in mind, one might wonder as to why experts are advocating vaccination of children against COVID-19. After all, it does not seem to be as much of a major problem in children as it is in adults and the elderly. In addition, up to now, there have been only scarce amounts of data regarding the safety and effectiveness of the vaccines in children and it was difficult to arrive at a definitive conclusions regarding the requirements to vaccinate children and young people.

There is no question as to the need to vaccinate susceptible children, such as those who have co-morbid diseases, as they are more likely to get severe complications and die from the disease. Yet for all that, what about the need to vaccinate the other healthy children? In answer to that, there are a few other observations that need to be addressed. Children are more susceptible to catch the disease by virtue of the surroundings that they have to be kept in the classrooms of schools, the risks of catching the disease during travel to school in crowded public or private transport vehicles as well as the inevitable congregations of significant numbers of them in schools and playing fields. Those children who contract the virus can spread the disease even if they are asymptomatic. One must also remember that children and young people form a significant proportion of the population of any country and to arrive at the 70% coverage of the population as the Gold Standard for herd immunity, it is necessary to think of vaccinating them as well.

We, in this emerald isle, have now vaccinated children with comorbidities which make them that much more vulnerable and susceptible to die. Currently children over 15 years and up to 19 years are being vaccinated with the Pfizer vaccine with the trade name “Comirnaty”. As this vaccine is licensed for Emergency Authorisation Usage in children over the age of 12 years, it is most likely that Sri Lankan children from 12 to 15 years may also be vaccinated soon. That decision will be made after careful consideration of several medical details. In contrast to the Pfizer Comirnaty vaccine, the Oxford AstraZenica vaccine is currently licensed to be used only in persons above the age of 18 years. Results of some on-going research trials in the usage of that vaccine in those under 18 years of age are awaited.

The burning question in medical circles at present is what about children under the age of 12 years. Should they be vaccinated? A few weeks ago, closer to a month or so, Pfizer Inc., submitted the data of their clinical trials on the efficacy and safety of their Pfizer Comirnaty vaccine directly to the United States Food and Drug Authority (FDA) for licensing its usage for children over five years of age. They submitted the data before they were peer-reviewed and published in any research journal. That modus operandi came under some flak as the company has a previous history of concerns being expressed in medical circles as a company that uses ‘aggressive pharmaceutical marketing’ and was also alleged to have been involved in several other ethical misdemeanours (https://en.wikipedia.org/wiki/Pfizer).

However, in this instance, Pfizer appears to stand vindicated because the results of the study have now been published in the reputed New England Journal of Medicine on 09th November 2021. It is an on-going research study in children over six months of age, going up to 11 years of age. The paper presents very convincing data in children over five years of age going up to 11 years. The company has not provided analytical data for children under five years of age. The entire project consists of an Open-Label Phase 1 dose-finding study, together with on-going Phase 2 and 3 randomised placebo-controlled studies.

In the Phase 2–3 trial, participants were randomly assigned in a 2:1 ratio to receive two doses 21 days apart of either the Pfizer BNT162b2 Comirnaty vaccine at the dose level of 10-μg, identified during the open-label Phase 1 study, or placebo, respectively. Immune responses 1 month after the second dose of the vaccine were immunologically bridged and compared to those in 16-to-25-year-olds from the pivotal trial of two 30-μg doses of BNT162b2. Vaccine efficacy against Covid-19 at seven days or more after the second dose was assessed. They also looked at the adverse effects profile and the researchers found no significant incidence of any serious side-effects of the vaccine, including even the rare myocarditis and pericarditis.

Based on the results, the researchers concluded that “A Covid-19 vaccination regimen consisting of two 10-μg doses of BNT162b2 administered 21 days apart was found to be safe, immunogenic, and efficacious in children five to 11 years of age”. It must be noted that the dose used is one third of the 30-μg dose used for adults and the elderly. In addition, one may speculate that Pfizer had decided to present the data directly to the FDA before the paper was published in a journal because of the unavoidable delay in publishing the accepted articles in scientific medical journals. One could now well understand that as a reason for the pathway that Pfizer Inc., had elected to take in the very recent past.

Taking into account all this information, the local experts in the medical field will have to make appropriate decisions regarding COVID-19 vaccination in children under the age of 15 years. It will necessarily involve serious consideration being given to many complex aspects of the entire scenario. It would indeed be a daunting task for the decision-makers, very specially the Sri Lanka College of Paediatricians, which is the premier academic organisation principally involved in child healthcare. However, it must be unequivocally stated that a prerequisite for such decisions would be the mandatory licensing of any vaccine against COVID-19 by internationally recognised licensing authorities for the under 12-year age group.