This study is exploring new COVID-19 vaccines for safety and effects in children and adults aged 5 and older. The vaccines being tested are called BNT162b2. To join, participants must be medically stable, not have had a recent COVID-19 infection or vaccination, and not have had certain other vaccines recently. If you are between 5 and 64, you need to have a medical condition that makes you more likely to get very sick from COVID-19.

Participants will belong to either Cohort 1 or Cohort 2. In Cohort 1, participants will receive a known dose of the vaccine. In Cohort 2, participants will get one of three possible vaccines, but they won’t know which one. The study lasts about 6 months and requires at least 3 visits. During these visits, you'll record any side effects and keep a diary about your health. The study team will also collect nose swabs and blood samples.

• Duration: The study lasts for about 6 months.
• Visits: At least 3 study visits are required.
• Health Monitoring: Participants will record side effects and give nose swabs and blood samples.