August 15, 2021
As promised, here’s an out-of-tour update on vaccinating children after some of you asked me about it. Let’s start with the basics:
Children and adolescents aged 12 years and older are already being vaccinated with mRNA vaccines, clinical trials for children under 12 years are ongoing. Basically, it remains the case that children and adolescents are at less risk of severe SARS-CoV-2 infection than adults. However, children and adolescents can also contract and transmit the virus.
Recently, however, there have been increasing reports of clusters of more severe illness in children (last week, for example, 1,600 children with SARS-CoV-2 infections were admitted to hospitals in the US). This could be because the delta variant is more contagious and also replicates faster and in greater numbers in the body.
But it could also be – and there are only a few studies on this topic– that the rate of severe disease in the age group has not changed and that there are simply more infections in children due to the delta variant and thus more severe cases.
Back to Vaccines – What Do We Know?
Basically, the RNA vaccines are safe and effective in the 12-16/18 age group. Here, for example, is a new study with Moderna’s mRNA vaccine among about 3,700 teenagers aged 12-17. Of course, a great many doses of mRNA vaccine have now been given to 12-18-year-olds. When you vaccinate a large number of people, you also find quite rare side effects.
So far, one side effect has been found to occur mostly in male adolescents (16+) and young adults, and that is mostly quite mild myocarditis. Taken together (adults and adolescents), about 1,250 heart muscle inflammations have been reported in the US to date, and 730 appear to be truly related to vaccination. Just as a reminder, 351 million doses of vaccine have been given in the US tuntil now. So the risk is low, even if you just look at the appropriate age group (it’s about 40 cases per million male vaccinated in the 12-29 age group, https://www.cdc.gov/mmwr/volumes/70/wr/mm7027e2.htm).
So those are the basics. By the way, the 12-16/17 age group currently gets the dose that adults get (30ug RNA at Pfizer, 100 ug RNA at Moderna). Pfizer and Moderna have meanwhile started clinical trials to test the respective vaccines in the age group below 12 years. And that’s where reduced doses are being tested.
Tests Under Way
Pfizer originally tested doses of 30, 20 and 10 ug of RNA, but now appears to be focusing on a 10 ug dose for 5-11-year-olds and a 3 ug dose for the 6-months to 5-years age group. Pfizer expects results for the 5-11-year-olds in September, for the 2-5-year-olds group shortly thereafter, and for the 6-months to 2-years age group in October or November.
Moderna seems to have gone down with the dosage at least from 100 to 50 ug, but it’s not quite that clear from the published clinicaltrials.gov entries. I assume Moderna will have initial data fairly soon as well. The trials include a few thousand children at Pfizer and about 13,000 children at Moderna (all told).
Where AstraZeneca currently stands with a vaccine for children is not clear to me.
Low Risk, But Not No Risk
In summary, children have less risk, but by no means no risk. For the risk-benefit calculus to work, vaccines have to be very safe. Based on this consideration, reduced doses are being tested. Initial results are expected in September, but it may take some time before approval is granted.
If the vaccine is safe (which I assume – but we have to wait for the data), I would definitely recommend getting it for the protection of the children themselves, but also for the protection against transmission to others.
You will get my next regular update on August 30.