Yes. Doses administered up to 4 days before the minimum interval, known as the 4-day grace period, are considered valid. This applies to primary series and booster doses of vaccine. Do not use the grace period to schedule doses. If a dose is administered earlier than the grace period, see Appendix D for guidance on corrective actions. A dose administered earlier than the grace period is considered a vaccine administration error; you are required to report COVID-19 vaccine administration errors to the Vaccine Adverse Event Reporting System (VAERS). Doses administered at any time after the recommended interval are valid. For more information, see timing, spacing, and interchangeability of COVID-19 vaccines.