• July 20, 2021

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By: Annemieke Aartsma-Rus, Ph.D.

Safety, Immunogenicity, and Efficacy of the BNT162b2 Covid-19 Vaccine in Adolescents. Frenck et al. N Engl J Med. 2021 May 27; DOI: 10.1056/NEJMoa2107456

While waiting in line to receive my second Moderna Covid-19 mRNA vaccine, I read the recent paper on evaluating the safety, immunogenicity, and efficacy of the Pfizer/Biontech Covid-19 mRNA vaccine in adolescents. It seemed fitting to discuss in this first President’s Pick.

I do not think I have to explain the pandemic and COVID-19, the disease caused by infection with SARS-CoV-2 commonly referred to as ‘the Coronavirus’. In children, infection is often asymptomatic or associated with mild symptoms. However, children can pass on the virus to adults, such as parents, grandparents, and teachers, including those who are at risk for developing severe COVID-19. Additionally, some children themselves will develop a severe disease that requires hospitalization and/or have long lasting negative effects. In the Netherlands, a country of ~17 million inhabitants, it is estimated that 350 children under 16 years are still suffering from long term effects of their COVID-19 infection.

Finally, there are children with fragile health, e.g. those with severe asthma, cancer, or genetic or acquired diseases that impair respiratory function. For those, the risks of contracting severe COVID-19 that results in permanent health issues or even death are high. As someone working on Duchenne muscular dystrophy, a progressive muscle wasting disease associated with respiratory insufficiency and cardiomyopathy where patients also have a suppressed immune system due to chronic use of corticosteroids, I know that many Duchenne families have been in self-imposed quarantines for well over 18 months out of fear of their son or brother contracting COVID-19.

In light of all this, I was very happy to see the results of the clinical trial testing the Pfizer/Biontech mRNA Covid-19 vaccine in 12 to 15-year-old children. The aim of the study was to test the safety and efficacy of the vaccine. 2,264 children participated, of whom 1,129 received placebo and 1,131 the vaccine. The vast majority (97%) received both doses of placebo or vaccine.

Both placebo and vaccine injected children experienced injection site pain, but severe injection pain was only reported by those receiving the vaccine (1.5%, compared to 3.4% of 16 to 25-year-olds). Other side effects included headache, fatigue, and fever (20% of patients). These side effects were experienced much more frequently after the 2nd dose than the first. Two children experienced severe adverse events, one in the placebo group and one in the vaccine group. Neither were thought  to be related to the vaccine.

My own experience with the Moderna vaccine is similar. I would describe the injection site pain 1-2 days after the first vaccination as severe. After the second vaccination, the pain was less severe, but I did develop chills 13 hours post vaccination and then a fever of 39.1 degrees Celsius (102.38 Fahrenheit) 14 hours post vaccination, which then gradually went down over the next 24 hours. (As a scientist, I monitored this closely of course.)

For efficacy, the goal was to show that the immune response of 12 to 15-year-olds was not worse than that of 16 to 25-year-olds (non-inferiority). In fact, titers of the 12 to 15-year-olds were higher. Fifteen of the 2,264 participants later contracted Covid-19; 12 in the placebo group and 3 in the vaccinated group. Of the latter, all were infected within 11 days after receiving their first vaccination. Based on these results, the FDA approved the Pfizer/Biontech vaccine for use in 12 to 15-year-old children.

When I tweeted a summary of the paper in my daily paper tweet (#apaperaday; @oligogirl), this elicited discussion. Vaccinating children will increase herd immunity and will reduce the risk of fragile children and adults contracting the disease – some of whom cannot be vaccinated. However, children generally only experience very mild symptoms or no symptoms at all when infected with the coronavirus. Is it then defendable to vaccinate them knowing that ~20% will develop side effects? Similar discussions have been happening at work and in my own extended family. Initially in the Netherlands, only ‘at risk’ children below 16 years were to be vaccinated with the Pfizer/Biontech vaccine. However, as of early July, these children can be vaccinated if they want to. As I am neither a virologist nor an epidemiologist, I will refrain from giving any advice.

What I am is an oligonucleotide scientist – and a proud one – because the oligonucleotide therapy field is delivering again. It seems that the stars aligned for the mRNA vaccines and the tools and expertise needed were available when the world needed them. As an ‘insider’ I know that it took many years of hard work and dedication to come to this point.