Mild reactions were experienced in 46% of recipients.
A new study demonstrated that there were no unexpected reactions to COVID-19 vaccination in a very young pediatric population (6 to 24 months old). These participants received at least 1 dose of either of the FDA approved mRNA COVID-19 vaccines (Pfizer-BioNTech or Moderna).1
The most common reactions reported were the following: irritability or fussiness (30.1%), local reactions (21.1%) and fever (13.8%).1
Overall, 46.7% of recipients had a reaction with 21% had local reactions (at the injection site), and 38.8% had systemic reactions (fever, irritability). 1
“Among children with reported reactions, 18 of 56 (0.3%) experienced reactions described by participants as severe. In total, 87 of 5644 children (1.5%) were reported to have received care from a health care professional for a reaction after any dose (BNT162b2, 45 [1.8%]; mRNA-1273, 42 [1.4%]). Six participants reported a seizure or febrile seizure after receiving COVID-19 vaccination. No deaths were reported,” the investigators reported.
The study was published in JAMA Network Open this week.
The study included participants from the Centers for Disease Control and Prevention (CDC) COVID-19 Vaccine Pregnancy Registry (C19VPR).2 The registry was developed to monitor vaccine safety of mothers and their infants. Data is collected via phone interviews and reviewing medical records. To be considered for inclusion, individuals needed to receive a COVID-19 vaccine in pregnancy or up to 30 days prior to their pregnancy-associated last menstrual period.2 Overall, this specific study included 5,644 young children up to the age of 2 who received at least 1 dose of a mRNA COVID-19 vaccine.1
In terms of the specific vaccine immunization, the Moderna vaccine was given to 52.7% of participants and the Pfizer-BioNTech vaccine was given to 45.5% of the participants. And 20% of the children received another vaccine along with the COVID-19 vaccine.1
Severe reactions were rare, with only 0.3% described as severe and 1.5% of children requiring professional care after vaccination. No deaths were reported.
Reactions were more frequent after the first dose compared to the second, particularly for Pfizer-BioNTech (39.1% after dose 1 vs. 28.1% after dose 2) and Moderna (40.7% vs. 33.1%).
Reactions were more common when another vaccine was administered alongside the mRNA COVID-19 vaccine.
According to the investigators, there were a few other takeaways including the following:
Reactions were more common after the first dose compared to the second dose. For the Moderna vaccine, after dose 1, 40.7% of recipients had a reaction; after dose 2, 33.1% of recipients had a reaction. For the Pfizer-BioNTech vaccine, after dose 1, 39.1% of recipients had a reaction; after dose 2, 28.1% of recipients had a reaction.1
This is a marked difference from previous studies in the literature. “In contrast to other studies observing a higher prevalence of reactions after the second COVID-19 vaccine dose, we observed a higher prevalence after the first dose. This difference may reflect maternal vaccination; the first COVID-19 vaccination in our cohort may be some children’s second immunological encounter with a COVID-19 vaccine,” the investigators wrote.1
Although there were similar rates of reactions in the first dose for the 2 mRNA vaccines, participants who received the Moderna vaccine did see more reactions after the second dose. The investigators also point out there were more reactions when another vaccine was given along with the COVID-19 vaccine.1
This study points to further evidence of the expectations for reactions for the youngest population in terms of mRNA COVID-19 vaccination.
“These findings add evidence indicating that mild or moderate local and systemic reactions may be experienced, but severe reactions and serious adverse events are rare,” the authors write.1
