Why developing Covid-19 vaccines for children takes time

Why developing Covid-19 vaccines for children takes time

 

Hundreds of millions of adults have been vaccinated against Covid-19, proving that the vaccines are safe and effective, but those results are not the research needed to decide whether the vaccines are safe for kids.   "We can't make assumptions about the safety or tolerability of medicines in children being the same as for adults," said Dr. Kari Simonsen, who is leading Pfizer vaccine trial at Children's Hospital & Medical Center in Omaha.   "As we are fond of saying in pediatrics: Children are not small adults. Children are children," said Dr. James Versalovic, interim pediatrician-in-chief at Texas Children's Hospital. "Their bodies are developing and will react differently, and we need to treat them differently."   Currently, adolescents as young as 12 can be vaccinated against Covid-19, but younger children aren't eligible yet.   Instead of enrolling the 30,000 people the companies needed for adult trials, the vaccine companies are building off of the adult trials and conducting what are known as "immunobridging" trials: looking for an immune response in children that is similar to adults.   Vaccine advisers to the US Centers for Disease Control and Prevention said in June there is a likely association between the mRNA Covid-19 vaccines and extremely rare cases of heart inflammation in adolescents and young adults, but the benefits of vaccination still clearly outweigh the risks. The inflammation cases appeared to be mild, and they resolved quickly on their own or with minimal treatment.   So out of an abundance of caution, in early August, the FDA asked the vaccine developers for six months of follow-up safety data, instead of the two months it asked for adult authorization. The agency also asked Pfizer and Moderna to double the number of children ages 5 to 11 in clinical trials.   Versalovic said it was no problem to recruit more kids for the Pfizer and Moderna trials. Many trial sites have long waiting lists. The trial expansion, though, added at least a month to the research process.   "We all agreed it was worthwhile, just to make the trials even more robust, data to provide that additional level of reassurance to parents across the country. It does lengthen the trial, but just a bit," Versalovic said.