Let's Look at the Actual Safety & Efficacy Data for Vaccines for Children reported by the FDA
"among participants 6 through 23 months of age, the vaccine was 50.6% effective in preventing COVID-19. Among participants 2 through 5 years of age...the vaccine was 36.8% effective..."
Coronavirus (COVID-19) Update: FDA Authorizes Moderna and Pfizer-BioNTech COVID-19 Vaccines for Children Down to 6 Months of Age
Immune response evaluated on only 230 children ages 6 most-23 months, 260 ages 2-5 years, 320 ages 6-11. 340 Adolescents 12-17 years old…
Adolescents tested BEFORE Omicron strain.
Children 6 months through 5 years of age
Immune responses of a subset of 230 children 6 through 23 months and a subset of 260 children 2 through 5 years of age who received a two-dose primary series of the Moderna COVID-19 Vaccine at 25 micrograms (mcg) of messenger RNA (mRNA) per dose were compared to immune responses among 290 adults 18 through 25 years who received two higher doses of the vaccine in a previous study which determined the vaccine to be effective in preventing COVID-19. In these FDA analyses, the immune response to the vaccine, of both age groups of children, was comparable to the immune response of the adults
An analysis of cases of COVID-19 occurring at least 14 days after the second dose among approximately 5,400 children in this age group without evidence of prior infection with SARS-CoV-2 was conducted during the time period in which the omicron variant was the predominant circulating strain. In this analysis, among participants 6 through 23 months of age, 64% of whom had blinded follow-up for more than two months after the second dose, the vaccine was 50.6% effective in preventing COVID-19. Among participants 2 through 5 years of age, 72% of whom had blinded follow-up for more than two months after the second dose, the vaccine was 36.8% effective in preventing COVID-19.