evidence: The updated vaccines, from Pfizer/BioNTech and Moderna, are available for those ages 6 months and older. The Food and Drug Administration approved the mRNA vaccines on Sept. 11 for those 12 years of age and up, and the FDA issued an emergency use authorization for children ages 6 months to 11 years old. The next day, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices voted 13 to 1 to recommend that everyone 6 months and older should get the shots, and the CDC endorsed that recommendation. [...] All of the Pfizer/BioNTech and Moderna COVID-19 vaccines — the originals, the bivalent boosters and the latest updates — use the same mRNA technology to trigger an immune response to the spike protein of SARS-CoV-2, the virus that causes COVID-19. The spike protein is what the virus uses to enter cells. The mRNA in these vaccines provides instructions for cells to make their own spike proteins, which subsequently generates protective antibodies and T cells in the body. [...] Some studies suggest that the shots may produce a lower immune response if given on the same day, although it is not clear if such a reduction is clinically significant, the agency says.