What to Do When a Vaccine Has a Temperature Excursion

A refrigerator alarm, power outage, or out-of-range data-logger reading can put vaccine stock in question. The first priority is to prevent an uncertain dose from being administered. A temperature excursion does not automatically mean every vial must be discarded, and a normal reading later does not prove the stock is still usable. Use the current product-specific guidance and the site’s written response plan.

What counts as an excursion

CDC’s 2026 Vaccine Storage and Handling Toolkit treats a reading outside the recommended range in the manufacturer’s package insert as a temperature excursion. Products differ: refrigerated, frozen, and ultra-cold vaccines do not all share one range, and some products have narrower or product-specific conditions. Check the current package insert or EUA fact sheet rather than assuming one standard temperature applies to every vaccine.

A temperature logger can show how far the reading moved, how long it remained out of range, and whether the excursion happened once or repeatedly. Record the device’s current, minimum, and maximum readings, the time discovered, the likely start time, the unit temperature, and any visible alarm or power issue. Do not reset or clear the logger before preserving the data required by the site procedure.

Take immediate protective action

1. Notify the primary or alternate vaccine coordinator or supervisor immediately.
2. Label affected vaccine “DO NOT USE.”
3. Separate it physically from usable stock while keeping it at the appropriate storage temperature.
4. Do not discard, administer, or return it to the shelf as usable until a viability decision is made.
5. Document the products, lot numbers, quantities, temperature data, time, and actions taken.
6. Follow the site’s excursion SOP and contact the manufacturer and immunization program as directed.

The “DO NOT USE” label is a control to prevent accidental administration while the decision is pending. It is not a disposal instruction. Keep the affected stock in the proper storage unit, segregated in a clearly marked container. If the unit itself has failed or cannot maintain the proper conditions, follow the emergency relocation procedure and move the stock to an approved unit at the correct temperature.

Build a complete incident record

Record facts that help the manufacturer or public health program evaluate viability: product and presentation, lot and expiration, number of doses, storage temperature range, excursion duration if known, whether the vaccine was exposed to light, whether it was previously reconstituted, and what monitoring device reported the event. Include the date and time of discovery, device readings, room conditions if required, power status, and any corrective action. Attach or preserve the logger report under the site’s policy.

Do not estimate the duration as exact if the evidence only gives a range. State what is known and what is uncertain. A missing data logger reading is not evidence that the temperature remained in range. Document the source of each recommendation and the person who authorized any return to use or disposal. Follow VFC or other publicly purchased vaccine program reporting rules when they apply.

Find and fix the cause

Once stock is protected, check what caused the excursion. A door left ajar, power failure, thermostat adjustment, blocked airflow, incorrect probe placement, or a failing unit can create different patterns. Avoid changing settings repeatedly before recording the original conditions. Correct an obvious problem if safe, then monitor the unit and follow the SOP. If the equipment cannot maintain the product’s required range, transfer stock according to the emergency plan and arrange service.

Avoid these common mistakes

• Do not assume that a brief excursion is harmless or that freezing is safe for a refrigerated vaccine.
• Do not use the vaccine based only on appearance.
• Do not discard stock before receiving a viability decision unless directed by the responsible authority or policy.
• Do not mix affected vials with usable stock.
• Do not use a household thermometer as a substitute for the required monitoring device.
• Do not clear logger data before documenting it.
• Do not apply one vaccine’s storage range or stability decision to another product.

Worked example: refrigerator alarm overnight

The morning technician sees that a vaccine refrigerator alarm recorded a low temperature overnight. The technician notifies the coordinator, records the current/minimum/maximum readings and available logger history, labels and separates affected vaccines, and keeps them at the proper temperature. The coordinator contacts the manufacturer and immunization program with lot, time, and temperature details. The technician does not administer or discard the vials while the decision is pending. Afterward, the facility documents the determination, updates inventory records, and corrects the unit or procedure that caused the excursion.

Exam takeaway

For a vaccine temperature excursion: notify, label “DO NOT USE,” separate, maintain correct storage, document, and contact the manufacturer or immunization program for a product-specific decision. Do not administer or discard stock while viability is unresolved. Follow the current CDC toolkit, package insert, program rules, and site SOP.