Vaccine may lose potency rapidly if not stored according to the manufacturer’s instructions. However, it may still be permissible to use vaccine that has not been properly stored. Put the affected vaccine vials into the freezer after you have marked them so they are not confused with the unaffected vials, then call the manufacturer at 1-800-9-VARIVAX (1-800-982-7482) for further guidance about whether the vaccine is still usable. Unreconstituted varicella vaccine may be stored in the refrigerator for up to 72 hours before use. If refrigerated varicella vaccine is not used within 72 hours, it should be discarded.
If you have inadvertently left your vaccine at room temperature instead of in the freezer or have experienced a power failure, label the affected vaccine to keep it separated from unaffected vaccine and return it to recommended storage conditions in a freezer promptly, then contact the manufacturer for further guidance. Do not administer the vaccine until you have consulted with Merck.