The vaccine that is offered to children six months to eleven is a smaller dose of the same Pfizer vaccine and Moderna vaccine that has been used safely since December 2020. 8.5 million children aged five to eleven have been fully vaccinated and over half of all kids twelve to seventeen have been fully vaccinated, that is more than 15 million kids. It is safe and very effective in preventing illness from COVID-19 in kids.
Based on strong evidence that the vaccine is safe and effective, Pfizer received authorization from the CDC on May 12th 2021 to administer its vaccine to twelve to fifteen year olds, November 2nd 2021 to administer to five to eleven year olds, and June 18th 2022 to administer to six months to four year olds. Moderna received authorizations form the CDC on June 18th 2022 to administer its vaccine to six month to five year olds and on June 24th to administer to six to seventeen year olds.
You can find additional information on the testing of COVID-19 vaccination at COVID-19 Vaccine Safety in Children and Teens | CDC