This study will evaluate the safety and immunogenicity of the mRNA-1273.214 vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concerns (VOCs) in participants aged 6 months to \<6 years, when administered as a primary series in SARS-CoV-2 vaccine-naïve participants (Part 1) and a single booster dose (BD) given to participants who previously received 2 doses of the mRNA-1273 vaccine as a primary series (Part 2); and will evaluate the safety and immunogenicity of the mRNA-1273.815 vaccine, when administered as a BD in participants aged 6 months to \<6 years (Part 3) and when administered to SARS-CoV-2 vaccine-naïve participants aged 2 years to \<5 years of age (Part 4).
Part 1 will enroll participants aged 6 months to \<6 years who have not been previously vaccinated against SARS-CoV-2. Participants will receive 2 doses of the mRNA-1273.214 vaccine. Part 2 will enroll participants aged 6 months to \<6 years who have previously been vaccinated with a mRNA-1273 primary series in Study mRNA-1273-P204 (NCT04796896). Participants will receive a single BD of the mRNA-1273.214 vaccine, at least 4 months after completion of the mRNA-1273 primary series. Part 3 will enroll participants aged 6 months to \<6 years who have previously been vaccinated with an authorized/approved COVID-19 vaccine. Participants will receive a BD of the mRNA-1273.815 vaccine at least 4 months after the last receipt of a COVID-19 vaccine. Part 4 will evaluate mRNA-1273.815 vaccine administered as a single dose to SARS-CoV-2 vaccine-naïve participants aged 2 years to \<5 years of age enrolled in Cohort A (Part 4A), compared to 2 doses given to SARS-CoV-2 vaccine-naïve participants aged 6 months to \<2 years enrolled in Cohort B (Part 4B).
Sterile liquid for injection
Sterile liquid for injection
CABA, Buenos Aires F.D., Argentina
Buenos Aires, Ciudad Autónoma de BuenosAires, Argentina
San Miguel de Tucumán, Tucumán Province, Argentina
Buenos Aires, Argentina