Recent approval for Covid-19 vaccines to be administered to five to 11-year-olds in the US means that 28 million young people are now eligible to be immunised.
The US Centres for Disease Control and Prevention (CDC) gave the green light for the Pfizer-BioNTech vaccine, following advice late last month from the Food and Drug Administration (FDA).
FDA documents indicate that the Pfizer-BioNTech vaccine has 90.7 per cent efficacy in children aged five to 11, which means that it prevents more than 90 per cent of cases of Covid-19.
Children aged five to 11 will be given two doses three weeks apart, with each dose containing 10 microgrammes of messenger RNA (mRNA) – one third as much as people aged 12 and above receive.
It comes after regulatory authorities in some other countries also approved Covid-19 vaccination for children.
In October, the UAE approved the Pfizer-BioNTech shot for five to 11-year-olds, two months after it green-lit the Sinopharm vaccination to be administered to three to 17-year-olds. China approved its own Sinovac jab for three to 17-year-olds in June.
Whether coronavirus vaccines should be given to children has sometimes sparked controversy because youngsters are less at risk from Covid-19.
Here we consider the data on the costs and benefits.
How much are children at risk from Covid-19?
Although it became apparent early on that older people were in greater danger from Covid-19, young people can also become seriously ill and die.
Experts say there are three risks: severe Covid-19, multisystem inflammatory syndrome in children (MIS-C) and the chance that symptoms will persist, or long Covid.
By the beginning of October, there had been 5,217 cases of MIS-C reported in the US, with the average age of affected children being nine. About two-thirds of cases result in an admission to intensive care, and one to two per cent prove fatal.
According to the CDC, there are between 100 and 600 cases of MIS-C per million SARS-CoV-2 infections.
While long Covid is less common in children than in adults, seven to eight per cent of children who have Covid-19 report continuing symptoms 12 weeks later, according to UK figures.
Between October 3, 2020, and October 3, 2021, 66 children aged between five and 11 died in the US from Covid-19, making it one of the 10 biggest causes of death in the age group.
Children remain at much lower risk than adults of severe illness, however.
“Unless they have any underlying comorbidities, the younger ones are at even less risk of severe disease and hospitalisation and death,” said Dr Andrew Freedman, an infectious diseases specialist at Cardiff University in the UK.
What are the risks of vaccination?
Vaccine trials on children aged five to 11 have not highlighted serious risks, with side effects of the 10 microgramme dose being similar to those experienced by adults. The CDC describes them as “mild” and “self-limiting”, with a sore arm most common.
In adolescents and young adults, particularly males, there have been cases of myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the pericardium membrane around the heart) after vaccination, especially with Pfizer-BioNTech or Moderna (which is another mRNA vaccine) although, in the vast majority of cases, there were no long-lasting effects.
The risks of myocarditis and pericarditis from vaccination are lower than those from an actual Covid-19 infection.
A US study suggested there were about 11 cases of myocarditis for each 100,000 vaccinated males aged 16 to 29, the age group, who are thought to be most at risk.
For comparison, other US research found that there were 450 cases of myocarditis per million Covid-19 cases for males aged 12 to 17, and 213 per million Covid-19 cases for females aged 12 to 17.
The Pfizer-BioNTech vaccine trials involving five to 11-year-olds did not show up cases of myocarditis or pericarditis, although the numbers of children involved in the trials, 3,100, may have been insufficient to highlight such a rare side effect.
Doctors think very young children may be less likely than older children to develop myocarditis or pericarditis because the condition could be linked testosterone levels, which increase in adolescent males.
Dr Freedman said some people have argued that children are “routinely” given vaccinations against diseases they are much less at risk from than Covid-19.
“If you go with that argument, the risk-benefit would be in favour of immunising younger children,” he said.
What other benefits may result from vaccinating children?
As well as reducing the risk that Covid-19 will harm the children themselves, vaccinating young people makes it less likely that they will spread the coronavirus.
Younger children are, however, thought to be less likely than older children or adults to become infected and spread the coronavirus.
The argument that children should be vaccinated because it protects others who may be more vulnerable raises ethical questions.
Dr Freedman said vaccinating children may not be ethical if it were of no benefit to them as individuals, but he emphasised this was not the case.
“It is of benefit to them,” he said.
“Even if the risk contracting [Covid-19] may be small, it’s not zero.”
Vaccinating children has the added positive, he said, of reduce disruption to education, as youngsters are more likely to be able to remain in school.
Prof John Oxford, professor emeritus at the University of London, said he was “very positive” about vaccinating children against Covid-19.
Experience with influenza showed, he said, that vaccinating children protects them and prevents the spread of the virus to their parents and grandparents.
There is limited knowledge of the long-term effects of Covid-19 in children or adults, he added, so vaccinating young people protected them from potential long-term consequences that may as yet be unidentified.
“I cannot see children getting away scot-free. As a virologist, it doesn't make sense. We don't know the long-term effects in children,” he said.
Prof David Taylor, professor emeritus of pharmaceutical and public health policy at University College London, said vaccinating children "prepares the immune system for later in life" when the risks of Covid-19 would be higher.
"It's probably safer for the children to have the vaccine than this disease, even though the risks are low," he said.
