Ask the Experts: Varicella (Chickenpox): Storage & Handling

Live varicella-containing vaccines (varicella, MMRV) must be stored in a freezer at a temperature between -50°C and -15°C (between -58°F and +5°F) until reconstitution and administration. These vaccines can deteriorate rapidly after they are removed from the freezer. A separate stand-alone freezer or a combination refrigerator-freezer purpose-built for vaccine storage (sometimes called “pharmaceutical grade”) should be used to store frozen vaccines that require storage temperatures between -50°C and -15°C (between -58°F and +5°F). A stand-alone storage unit that is frost-free or has an automatic defrost cycle is preferred. Frozen vaccines should not be stored in the freezer compartment of a household-type combination unit because household freezers in combination units cannot reliably maintain proper storage temperatures for frozen vaccines. This applies to both temporary and long-term storage of frozen vaccines. The diluents should be kept separately in the refrigerator or at room temperature. Live varicella-containing vaccines must be administered within 30 minutes of reconstitution.

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.

Yes. According to the manufacturer, unreconstituted varicella vaccine may be stored at refrigerator temperature (2°C to 8°C, 36°F to 46°F) for up to 72 continuous hours prior to reconstitution. Vaccine stored at 2°C to 8°C that is not used within 72 hours of removal from -15°C (+5°F) storage should be discarded. See www.merck.com/product/usa/pi_circulars/v/varivax/varivax_pi.pdf.