Vaccinating children and teens could be key to stifling the pandemic, experts have said, as clinical trials begin to test Covid-19 vaccines in young people.
While Covid-19 is associated with a considerably lower burden of morbidity and mortality in young people, and there is evidence that children may be less likely to acquire the infection, the role of children in transmission is unclear, according to the Royal College of Paediatrics and Child Health.
Until everybody – including children – is vaccinated, said John Edmunds, a member of the UK government’s Scientific Advisory Group for Emergencies (Sage) on Sunday, there remained a “significant risk of a resurgence” of the virus.
The virus can also cause asymptomatic infections across all age groups, so, in a sense, immunising children will protect the elderly, added Stanley Plotkin, who invented the rubella vaccine, co-invented the rotavirus vaccine and helped develop other vaccines, including those for anthrax, polio, and rabies.
“I cannot imagine how we could even hope to eradicate the virus, unless we are willing to immunise the majority of the population,” he said.
Researchers behind the Oxford/AstraZeneca vaccine have launched a mid-stage study to test their Covid-19 vaccine in children aged between six and 17.
Other Covid-19 vaccine makers have also begun – or are scheduled to start later this year – their own studies in adolescents and young children. Pfizer/BioNTech expects to share data from its study of 12- to 15-year-olds in the coming months, and begin a study of five- to 11-year-olds in due course.
Scientists expect that that unlike adolescents who have relatively similar immune responses as adults – those below 12 years of age will require a potentially modified formulation or dosing schedule.
Data on how safe and effective the different vaccines are in younger age groups should start to come in by this summer and beyond. But underlying the argument in favour of vaccinating children – apart from preventing the rare cases of severe illness and long Covid – is how well vaccines are able to thwart transmission across different variants.
There are hints that some vaccines authorised for use are reducing the spread of the virus, but the data is not yet conclusive, scientists cautioned.
If the vaccines are proved to have a strong enough effect on transmission – then assuming all adults are inoculated by some point this year, the only age-groups largely driving the spread of the disease will be the young, highlighted Dr Rinn Song, a paediatrician and clinician-scientist with the Oxford Vaccine Group.
Paul Heath, the professor of paediatric infectious diseases at St George’s, University of London, and the principal investigator of the UK arm of the Novavax Covid-19 vaccine trials, said ongoing infection in children would potentially be a reservoir of infection for unvaccinated adults and the elderly.
“And so, it may still be a reasonable strategy therefore to vaccinate children so that they can’t transmit to those susceptible adults.”
Another reason to vaccinate children could be to secure educational settings, added Adam Finn, professor of paediatrics at the Bristol Children’s Vaccine Centre, who is part of a team conducting paediatric Covid-19 vaccine studies at the University of Bristol.
“If you can show that by immunising children you can make education guaranteed … and remove the risk of it being disrupted, then that’s a direct benefit to them.”
However, he cautioned, that for many vaccines designed to protect against infectious diseases it is usually possible to get outbreaks under control without immunising everyone. “So if, for coronavirus, it turned out that we really do have to immunise everybody that would be an exception – it wouldn’t be the rule,” he said.
“I think it’s still an open question as to how far we’re going to need to go with this [vaccination] programme in order to get things under control … I would say that it’s more likely than not, that by the end of this year we will be using vaccines in children under the age of 18. But I don’t think it’s a certainty, I think it’s a likelihood.”
However, with the finite arsenal of global vaccine supplies, a key argument against vaccinating young age-groups in the near future is that high-risk groups in low and middle and income countries should be vaccinated first, said Song.
The decision to immunise children should be based on “whether or not it needs to be done”, added Finn. “And if it doesn’t need to be done, you shouldn’t do it.”