When to Use the 4-day Grace Period

The 4-day grace period is the 4-day period before the minimum interval for which vaccination can be considered valid.


  • Do schedule appointments according to the recommended interval (i.e., 0, 21-day interval). Do use the 4-day grace period to determine valid doses only when retrospectively reviewing records.
  • Count doses as valid if inadvertently administered within a grace period of 4 days or less (e.g., 17 through 20 days after the first dose, 24 through 27 days after the second dose or additional primary dose for moderately to severely immunocompromised people, or within 4 days of the 6-month interval for those receiving a booster dose).
  • Consider doses as vaccine administration errors if administered before the grace period. Primary series doses and additional primary doses administered before the grace period should be repeated. Booster doses administered before the grace period should not be repeated.


  • Do NOT use the 4-day grace period to schedule appointments.
  • Do NOT schedule appointments for the second dose earlier than recommended

Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Approved or Authorized in the United States




Page last reviewed: December 3, 2021