Questions and answers on COVID-19 vaccines for children

Children are not just small adults. They grow, their immune system develops, and they can catch other diseases than adults. They might not react the same to the vaccine, perhaps the dose should be different, and perhaps they will need more or fewer jabs. All of this makes it important to study the efficacy and safety of vaccines in children.

Vaccine manufacturers are required to perform clinical studies in children of all ages, and the vaccines are only authorised if the studies establish them to be effective and safe. The EMA experts who sit on the Paediatric Committee (PDCO) have decided the number of required paediatric studies, age groups and how the trials should be constructed. For each vaccine, a paediatric investigation plan (PIP) has been worked out. All PIPs are available at the website of the EMA, one of which is the Pfizer/BioNTech PIP. The website also provides information about other requirements imposed on vaccine manufacturers in regard to studies in children.

It has been assessed if the vaccine produces the same effect on the immune response and the development of antibodies against coronavirus in the 12 to 15-year-olds compared to the 16 to 25-year-olds. In the subsequent assessment of the vaccine for the 5 to 11-year-olds, the level of antibodies produced at a 10 micrograms dose was compared to the levels produced at a 30 micrograms dose in the 16-26 years age group.

It is also observed how many are infected with COVID-19 in the vaccine and placebo groups, respectively. In the Pfizer/BioNTech study, none of the trial participants aged 12 to 15 given the vaccine caught COVID-19, whereas 18 in the placebo group did. There were three children among the 5 to 11-year-olds given the vaccine who were infected with COVID-19 compared to 16.

in the placebo group. Note, however, that the studies in children were a lot smaller than the major study based on which the vaccine for adults was approved, so the statistical uncertainty is higher. For this reason, the studies in children are conducted last to enable a comparison with the major studies in adults and the knowledge acquired about the vaccine after its roll-out to the older age groups.

Small children aged 5 to 11 require a lower dose than older children and adults, but they need two vaccine jabs like anyone else. Whereas small children should be given a dose of 10 micrograms, children aged 12 and over should be given 30 micrograms. The reason is that a lower dose proved just as sufficient and efficient for vaccinating small children.

No, nothing suggests this to be the case. We have extensive experience of vaccinating children with all childhood vaccines. The study examining Pfizer/BioNTech in children aged 12 to 15 revealed the same side effects after vaccination as those observed in adults. This was also the case in the studies of small children aged 5 to 11. Also, throughout our monitoring of the vaccines, we have not identified any side effects among the 12 to 15-year-olds to suggest that they respond differently to the vaccines than others do. The reported side effects primarily concern symptoms such as tiredness, headache and fever that pass in a few days. The majority experiences no side effects. 

There is no known risk of long-term side effects in children or adults, and we do know that any developing side effects after vaccination tend to occur very shortly after vaccination. Vaccine manufacturers are bound by the conditional marketing authorisation to monitor the vaccines of the clinical trials for two years, which means we continuously receive new information from the manufacturers. Likewise, drug regulatory authorities around the world work together on the close monitoring of COVID-19 vaccines. The Danish Medicines Agency monitors the vaccines and all other medicines for as long as they are marketed in Denmark, and we assess all reports of side effects and react in response to unexpected or serious events.

It is standard practice to split studies of new medicines and vaccines into different age groups, investigating one group at a time. Teenagers and adolescents are first, then children a little younger and finally young children, infants and newborns. This way we can use the experience gained from older children first to determine if the dose should be lower/higher and to design studies in small children more accurately so as to keep the number of children participating in a clinical trial at a minimum. Children who participate in such trials are required to provide blood samples and fill out forms, and some might get a placebo, which offers no protection. So, it is all about recruiting only the number of children necessary to gain sufficient knowledge, no more, no less.