Vaccinating under-12s: risks and benefits merit careful consideration

Any decision to vaccinate all children under 12 years of age against COVID-19 must be made with due caution, considering in detail the risks and benefits, a recent review by international paediatric vaccine experts has warned.

It is worth noting though that the review doesn’t argue for or against vaccinating children against COVID-19 but rather highlights the points to consider and the complexity of policy decisions around vaccination of this age group.

“Whether all children less than 12 years of age should be vaccinated against COVID-19 remains an open scientific question,” said Murdoch Children’s Research Institute (MCRI) and University of Melbourne Professor Nigel Curtis. The review was led by MCRI and the University of Fribourg, and published in Archives of Disease in Childhood.

“The balance of risks and benefits of COVID-19 vaccination in children is more complex than in adults, as the relative harms from vaccination and disease are less well established in this age bracket,” Professor Curtis said.

It is important to consider vaccine decisions for infants, young children and adolescents separately and for data on the effectiveness and adverse effects to be continually reviewed, he said.

“Further data is needed to confirm that the benefits of the vaccine in preventing COVID-19 disease in children under 12 years of age outweigh any potential risks,” he said.

“Constant monitoring of COVID-19 disease severity across all age groups is crucial. If a variant of concern emerges with increased severity in children this would alter the risk–benefit equation.”

A phase two trial in 2500 children, aged 5–12 years, recently reported that an mRNA vaccine was safe, well tolerated and produced robust neutralising antibodies. Results from the same trial in children under five years of age are expected by the end of 2021.

The US Food and Drug Administration recently recommended Pfizer vaccines for children aged 5–11 years. The Therapeutic Goods Administration has indicated that young children in Australia could be eligible for a COVID-19 vaccine by the end of November, but long-term, real-world safety data will likely be required by Australian authorities before approving vaccines for this age group.

The review also pointed out that if COVID-19 remained a generally mild disease in children it may not be necessary to vaccinate all those aged under 12 years, which would reduce exposure to rare vaccine side effects, help improve the global vaccine supply and prevent any impact on routine immunisation schedules.

The University of Fribourg’s Dr Petra Zimmermann said that aside from protecting the small minority of children who become severely unwell with COVID-19, the key arguments for vaccinating healthy children were to protect them from long-term consequences such as long COVID and rare instances of multisystem inflammatory syndrome, as well as reducing community transmission and helping prevent school closures and the indirect harms of lockdowns.

“Routine immunisation programs for children and adolescents worldwide have been disrupted by the pandemic. Implementing a universal COVID-19 vaccine program for these age groups risks causing further delays by using up existing delivery resources and personnel. However, if COVID-19 vaccination is combined with the administration of other routine vaccines, this problem might be reduced,” Dr Zimmermann said.

In low- and middle-income countries where COVID-19 disease is more severe in children due to underlying health conditions, there may be a lower threshold for vaccinating children, Professor Curtis said.

“A one-dose or a reduced-dose vaccine might be an option for this age group, which might also lower the small risk of myocarditis experienced after a second dose of an mRNA vaccine,” he said.

Researchers from the University of Bristol, University of Oxford and The Royal Children’s Hospital Melbourne also contributed to the study.

Image credit: ©stock.adobe.com/au/Jacob Lund