Federal health advisories last week authorized COVID-19 vaccines for children under six months of age, the last age group to gain access to the vaccine. Some parents are wondering why it took so long, almost a year after the vaccine was first approved for adults.
“So as with any new product, research usually starts with healthy adults, and has to establish that the vaccine is safe and works in that group before it starts expanding to other vulnerable groups.” Give,” Dr. Don Nolt, pediatric infectious disease specialist at Oregon Health & Science University. “And the kids are usually the last in those groups.”
During Friday’s press conference with state health officials, Nolt also said that the youngest subjects are the hardest-hit during clinical trials.
“It’s hard to recruit kids to study,” Nolt said. “We know that parents are very eager to contribute to science and get their children involved in studies, but even so, it’s very easy to get thousands of adults over the age of 50.”
Children are also much smaller than adults, so finding the right dosage can be difficult. During clinical trials, researchers test different doses against each other in what is called a “dose taking” to see which works best with the fewest harmful side effects. are effective. These tests are usually done after researchers have already determined the highest tolerable dose.

Families wait their turn at a pediatric COVID-19 vaccine clinic for children ages 5 to 11 at Clackamas Town Center in this November 2021 file photo.
Christina Wentz-Graf / OPB
On June 15 a Food and Drug Administration advisory panel authorized vaccines for infants and children. The vaccines received final approval from the Centers for Disease Control and Prevention next Saturday. The decisions mean that COVID vaccines will soon be available to Oregon’s 230,000 children between the ages of 6 months and 5 years. State health officials say clinics should get supplies as early as Monday. Parents should contact their pediatricians or health providers for more information about scheduling appointments for their children.
The FDA authorized two different brands of COVID vaccines for children: Moderna and Pfizer. Moderna vaccine comes in two doses that are about one-quarter as strong as an adult dose. The Pfizer vaccine comes in three doses which is about one-tenth of the strength of an adult dose.
Because Moderna Vaccine is slightly stronger, the short-term side effects may be slightly worse than with Pfizer’s three doses. They usually start a day or two after vaccine administration, and they can last for 24 to 48 hours. Short-term side effects include irritability, drowsiness, and pain where the shot was injected. Some children may not experience any symptoms.
Each dose of Pfzier contains fewer active ingredients that help fight COVID, so they may take a little longer to take effect. Pfizer’s vaccine is considered effective about 80 days after the last dose, while Moderna’s vaccine is considered effective about 42 days after the last dose.
When deciding which vaccine brand to go with, Nolt suggests that parents go with the first one available.
“We want to emphasize that both vaccines will significantly reduce the child’s risk of infection and severe symptoms and hospitalization,” Nolt said. “If there is any uncertainty, families should discuss it with their child’s provider.”