(PAHO, Oct 28, 2021) — “It has nothing to do with safety risk when the shelf life of a vaccine is extended,” said PAHO/WHO Country Representative Dr Erica Wheeler.  Dr Wheeler, joined by her Washington based colleague, Dr Maria Luz Pombo, Advisor, vaccines and biotechnological products at the Medicines and Health Technologies Unit, provided clarity on questions around the extension of vaccines’ shelf life in their presentation at the Ministry of Health’s weekly press briefing on Wednesday 21st October.

In explaining PAHO/WHO’s regulatory role in the acquisition and distribution of vaccines, Dr Wheeler said that it was not uncommon to extend the shelf life of vaccines. Changes to approved conditions to vaccines are often needed. Vaccine shelf life is one of those and is established based on data generated by manufacturers over time. Appropriately, the WHO and other regulatory bodies: the European Medicines Agency, the Office of Vaccines Research and Review of the Center for Biologic Evaluation and Research and The Food and Drug Administration (FDA) decided to extend the shelf life of the Pfizer vaccine from six (6) to nine (9) months, when stored at -90° to -60°C, after a rigorous review of the data available. There was a robust recommendation for the extension.

Dr Pombo explained that regulatory bodies grant temporary authorisation for vaccines and other medical products during emergencies. Authorisation is based on a rolling review of data that manufacturers generate over time. Therefore, it is common to see new indications, temperature conditions, and shelf-life extensions because manufacturers develop data while products are in use. 

Stability studies for vaccines require simulation of the natural conditions that must be stored to meet quality standards. In the case of the Pfizer COVID-19 vaccine, those natural conditions are -90°C to -60°C for nine months. Nonetheless, this vaccine offers immunisation programs alternative storage conditions within the shelf life approved that practitioners need to be aware of: within the o months shelf-life of unopen vials may be stored and transported at -25°C to -15°C for a single period up to 2 weeks, and stability studies have demonstrated that upon removal from the freezer, one can store the undiluted vaccine for up to 31 days at 2°C to 8°C, prior use. 

In 2020, the various regulatory authorities approved Pfizer’s COVID-19 vaccine and the manufacturer gained WHO EUL certification in Dec 2020[1]. Since then, the manufacturer has submitted data to the Food and Drug Administration (FDA) in the USA and other regulatory authorities globally and to WHO to support changes to the conditions approved in the first review. Regulatory bodies and WHO have made a considerable effort to promote transparency of the conditions approved[2],[3],[4] so that practitioners and populations are well informed about changes that occurred based on the data available. 

WHO and other regulatory bodies based the decision to extend the shelf life of Pfizer’s COVID-19 vaccine on the submission of evidence of real-time stability data. This data assesses the quality attributes, physical appearance, and potency of the vaccine.  

Dr Pombo also noted the importance of implementing quality interventions to protect the integrity of the vaccines. Health practitioners and the immunisation program at the country level must keep records on the new shelf life to ensure the particular vaccine’s quality, safety, and efficacy.

PAHO recognises the need for fact-based information to clarify questions around the shelf life of COVID-19 vaccines and the process for approval. Visit PAHO.org for more information.