Corbevax for 5 -11 Year Olds: Should the Lack of Efficacy Data Worry You?

Corbevax COVID-19 vaccine has been recommended by the DCGI for kids between the ages of 5 and 11. Is it safe?

Corbevax COVID-19 vaccine for 5 to 11 year olds in India. (Representational image only)

(Photo: iStock)

COVID cases are once again on the rise in the country, following a global spurt in cases thanks to Omicron and its subvariants.

With schools running to full capacity and most children not protected by vaccines, the impending wave couldn't have come at a worse time for kids.

So far kids have been low on the priority list of vaccine recipients. But this might be changing, especially considering a large portion of the adult population in the country has been vaccinated with at least one dose.

The Subject Expert Committee (SEC) of India's Drugs regulatory body, Drugs Control General of India (DCGI) has recommended Biological E's Corbavax COVID vaccine for children between the ages of 5 to 11, and the vaccine has reportedly been granted a restricted emergency use authorisation by the DCGI.

Reports also suggest Covaxin has also been given the green signal by the SEC for the same age group.

An important caveat to keep in mind, though, is that an EUA doesn't necessarily mean the vaccines will be rolled out.

For the vaccines to be made available to the public, they must now be approved by the National Technical Advisory Group on Immunisation (NTAGI).

Vaccines for kids go through the same regulatory pipelines before they are granted an EUA, however as far as COVID vaccines in India are concerned, safety and efficacy data in the public domain is scarce.

For instance, no clinical trial data for Corbevax for this age group, or even in adults, is publicly available.

Does that mean they're not safe? Not quite.

FIT speaks to experts about safety and efficacy data on Corbevax for kids, and why the approval of COVID vaccines for kids has been trickier than those for adults.

COVID Vaccines for Kids in India: Where Are We?

On the eve of Christmas, Prime Minister Narendra Modi announced that COVID vaccines would be made available to kids over 15 years of age in the country. This was followed by an announcement that only Covaxin would be offered to this age group, although Zydus Cadila's vaccine was the first to be cleared for use in kids over 12.

In March, the Ministry of Health and Family welfare extended the vaccine coverage to 12 to 14 year olds as well, but this time, the vaccine of choice was to be Biological E's protein subunit vaccine, Corbevax.

The same one is set to be offered to 5 to 11 year olds now.

But, in the absence of efficacy and safety data, how do you know the vaccine is 'good enough' to protect the kids from this and any future waves of COVID?

Clinical Trial Data for Kids Has Been Tricky

Before COVID, vaccines were largely meant for kids and not adults, Dr Vineeta Bal, an immunologist from the Indian Institute of Science Education and Research (IISER) tells FIT.

"Because COVID was a pandemic, and it was absolutely chaotic, vaccines were developed very rapidly. In a sense there was a race to develop COVID vaccines."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)

So, she explains, the processes of a COVID vaccines' development is very different from traditional vaccine development. This applies to COVID vaccines for kids as well.

"Naturally a lot more testing was done (in adults) initially, not just where their numbers are large, but also efficacy was checked," she says.

According to Immunologist and Vaccinologist Dr Chandrakant Lahariya, this is one of the reasons efficacy isn't tested in kids.

"Efficacy requires large scale data, like atleast 30,000 samples. After that there is no separate efficacy trial."

Dr Chandrakant Lahariya

Instead, he says, in smaller children what is checked in clinical trials is immunogenicity and safety.

"You want to see whether the amount of antibodies which are being produced in the adults are being produced in children and through what does, what interval," says Dr Lahariya.

According to experts, some vaccines for kids were approved based on this immunogenicity data and not efficacy data.

"The alternative testing point explored is to ask if the vaccine triggers good antibody responses, with the assumption that good antibody responses will provide respectable protection. It appears that this latter point has indeed been tested for the vaccines being recommended/approved for children," explains Dr Satyajit Rath, immunologist at IISER Pune.

According to Dr Rath, it isn't that COVID vaccine trials in children are tricky per se, rather that COVID vaccine trials in general become tricky after a while when "many volunteers have already been pre-exposed, (and) a robust trial to test for real-life protection becomes less and less feasible."

Why Corbevax? Cost vs Benefit

Before it was green lit, not much was heard of the Corbevax COVID vaccine —and not much has changed since. Remember the kind of press Covaxin and Covishield got in the early days?

There is also the fact that Corbevax has not been approved or administered in any other country yet.

All of this has let to some apprehension among parents about the relatively new vaccine, with many choosing to 'wait and watch' before they let their kids take it.

The vaccine, Dr Bal says, isn't as new as you would think.

It's a tried and tested vaccine platform.

"Corbevax is much closer to the traditional vaccine and hence a robust method of vaccination that we are familiar with. Many of our vaccines that are currently in use are protein based vaccines, mixed with adjuvants," explains Dr Vineeta Bal.

"We have a history of using these vaccines, especially in the paediatric age group. So in that sense, I would consider Corbevax to be one fo the safer vaccines for this particular age group."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)

"Of course there will be some cases of allergic side effects which you can’t completely eliminate," Dr Bal adds.

"What is the frequency, and how do we balance the gains that are made by the vaccine against the problems which are created by the vaccine is what we have to see. I think the gains outweigh the problems by many fold."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)

...And it's also just more practical.

Many also have the question, 'why Corbevax, and not Covishield or Covaxin for young kids? After all we already have real world safety and efficacy data for these vaccines in adults.'

According to Dr Bal, "it is a matter of convenience that Corbevax has been recommended for the 5 to 11 age group."

Covishield, for one, has not been tested in kids below 18 at all. Covaxin, which is also up for DCGI clearance for the same age group has logistical manufacturing issues.

Covaxin, Dr Bal points out, was rolled out for kids over 15 but, "that wasn’t such a good idea because there weren’t enough doses available."

‘Transparency Would Have Helped'

The lack of clinical trial data in the public domain doesn't help cement confidence in the vaccines, although experts say this doesn't mean the vaccine is not trustworthy. Lack of transparency about the evidence is a problem.

"Ideally it should be made public, but there is no doubt that the trial data would have been accessed by the SEC and the DCGI. It is not available in the public domain, but the data is there," says Dr Lahariya.

Data for vaccines in adults is also not all there in the public domain to begin with. “Covaxin phase 3 trials data is not out. Zydus Cadila vaccine’s efficacy data has also not been published,” says Dr Bal.

“I would also feel extremely comfortable if the data is put out at least in medarchives or some such preprint servers so that there is at least access to the data. Transparency would go a long way."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)

To Vaccinate or Not Vaccinate Kids

Still wondering if your kids even need vaccines?

Experts are divided on this question. Dr Lahariya feels healthy children don't require COVID vaccines. "There is no data available for age distinction and severity of the Indian vaccines, but what we know is that healthy children in any age group have a low risk of poor outcome as far as moderate to severe disease is concerned," he says.

Dr Lahariya, however, adds that COVID vaccines should be offered to children with pre-existing health conditions.

On the other hand, Dr Bal is a strong advocate of vaccinating all kids.

"We have no seroprevalence data for children in the country, especially from rural areas," she says.

"Children do need vaccination because that will bring peace of mind to their parents and also the children can start going to school regularly and their disrupted social life, mental health, and academic life will probably start coming back to ‘normal’."

Dr Vineeta Bal, Immunologist, and researcher at the Indian Institute of Science Education and Research (IISER Pune)