Over the course of the pandemic, we have discussed in The Pulse the benefits of vaccines against SARS-CoV-2 (the virus that causes COVID-19). These discussions have included how COVID-19 vaccination during pregnancy protects the mother and also protects the newborn. We also have covered childhood vaccination against COVID-19. We did this in stages, as vaccines received emergency use authorization for children of different age groups, beginning with ages 16 and up, then 12 and up for the Pfizer-BioNTech mRNA vaccine (BNT162b2 “Comirnaty”), followed by ages 5‒11 for Pfizer-BioNTech, ages 6‒11 for the Moderna mRNA vaccine (mRNA-1273), the Pfizer-BioNTech ages 6 months to 4 years, and Moderna for ages 6 months to 5 years.
While there has been some concern about these vaccines triggering inflammation of the heart in teenage boys (who receive the same dosage that adults receive), this happens rarely and such cases are typically not severe. This means that certain medical tests – blood tests for proteins that leak from heart muscle when it is stressed and advanced imaging scans of the heart – reveal an inflammatory process without symptoms occurring. Because the risk of inflammation in the heart is lower than the risk of severe disease in teens infected with SARS CoV-2, the U.S. Centers for Disease Control and Prevention (CDC) continues to recommend vaccination for teenage boys.
The dosage of mRNA vaccine for children under 12 years old is less than what adults receive, and according to the CDC, there has been no observation of heart inflammation in the under-12 age groups from the vaccine. In a small fraction of children who become ill with COVID-19, there is a complication that develops a few weeks after recovery, called Multisystem Inflammatory Syndrome in Children (MIS-C). One complication of MIS-C can include heart inflammation. MIS-C is rare, but it tends to strike the 5- to 13-year age group in particular and it has killed children, just as severe COVID-19 disease has killed children. For this reason, the CDC recommends that everyone age 6 months and up be vaccinated.
What beckons now is COVID-19 vaccination for babies under 6 months of age. Currently, Moderna is recruiting participants for a Phase 2 clinical trial, called BabyCOVE, to test a version of its mRNA-1273 vaccine at an investigational dose that has been developed for infants. Infants between the ages of 12 weeks and less than 6 months will be enrolled and two different dosages of the vaccine will be tested. Each participant will be given a series of two injections. The trial will have two parts. The first part will consist of one arm (one test group) and will be open-label, meaning that there will not be a control group and that the researchers, and the parents of the babies, will know exactly what the babies are receiving. They will be getting two shots, each with a dose of 5 micrograms (mcg), spaced 8 weeks apart. This 5 mcg dose is 1/20th the dose that people ages 12 and up receive from each of the two injections of the Moderna primary series (100 mcg). It’s 1/10th the dose of what children ages 6 months to 5 years receive in each injection of the Moderna vaccine and what adults used to receive in the Moderna booster before that booster was replaced (50 mcg). It’s 1/5th the dose that children ages 6 to 11 years receive in their Moderna vaccines and what adults now receive of each mRNA sequence in the Moderna bivalent vaccine (25 mcg).
If safety of the 5 mcg dose is confirmed in the first part of the trial, the second part of the trial will begin, testing additional infants with a 10 mcg dose. As with the first part, this second part will move gradually in terms of the number or infants tested. Researchers will analyze the data on an ongoing basis, monitoring for safety signals, but also looking to see whether either or both dosages are effective in protecting infants against severe COVID-19.