Safety of Simultaneous mRNA COVID-19 Vaccine With Other Childhood Vaccines in Young Children

Inclusion Criteria: * Child 6 months through \<5 years of age at time of enrollment. * Child is due to receive mRNA COVID-19 vaccine and at least one other routinely recommended non-live vaccine per CDC or ACIP recommendations. * Parental/LAR intention of child receiving mRNA COVID-19 vaccine and at least one recommended non-live vaccine. * The parent/LAR must be willing and capable of providing permission for their child to participate through the written informed consent process. * The parent/LAR must be available for follow-up and must at minimum have telephone access. * The parent/LAR must agree to sign a medical release for the child so that study personnel may obtain medical information about the child's health (if needed). * The parent/LAR must be willing to delay COVID-19 vaccination for their child for up to 3 weeks. * The parent/LAR must be able to read English or Spanish. Exclusion Criteria: * History of any seizure (including febrile seizure) or first degree relative (biologic parent or biologic sibling including half-sibling) with a history of febrile seizure. * Contraindication to mRNA COVID-19 vaccine: A history of a severe allergic reaction (e.g., anaphylaxis) after a previous dose or to a component of the COVID-19 vaccine or a known diagnosed allergy to a component of COVID-19 vaccine. * A history of a severe allergic reaction (e.g., anaphylaxis) after a previous dose or to a component of a vaccine administered on the day of study enrollment. * For childre…