Anyone 5+ is eligible for a booster dose 5 months after completing your initial vaccine series.
Anyone 50+ or who received J&J as your primary series is now recommended to receive a 2nd booster dose of Pfizer or Moderna 4 months after your first booster dose.
Immunocompromised individuals are eligible for an additional dose 28 days after your initial series, a booster dose 3 months after your additional dose, and a 2nd booster 4 months later.