PAHO explains shelf-life extension of Pfizer covid19 vaccine

THE decision to extend the shelf life of Pfizer vaccines was nothing unusual and was based on data constantly gathered by Pfizer and sent to health authorities such as WHO, PAHO said in a statement on Thursday.

The statement quoted PAHO/WHO country representative Dr Erica Wheeler, who had spoken at the Ministry of Health's virtual briefing on Wednesday.

She said, "It has nothing to do with safety risk when the shelf life of a vaccine is extended."

Wheeler said it was not uncommon to extend the shelf life of vaccines, explaining PAHO/WHO's regulatory role in the acquisition and distribution 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."

She said after a rigorous review of available data, a decision was made to extend the shelf life of the Pfizer vaccine from six to nine months, when stored at -90 to -60 degrees C.

The extension was approved by WHO, the European Medicines Agency, the Office of Vaccines Research and Review of the Center for Biologic Evaluation and Research, and the USFood and Drug Administration (FDA).

"There was a robust recommendation for the extension," said the statement.

Further details in the statement came from Washington, DC-based Dr Maria Luz Pombo, adviser on vaccines and biotechnological products at PAHO's Medicines and Health Technologies Unit. She said 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."

Pombo said that to meet quality standards, the Pfizer vaccine must be stored at -90 degrees C to -60 degrees C for up to nine months.

She also said within this shelf life, unopened vials may be stored and transported at -25 degrees C to -15 degrees C for a single period up to two weeks, and stability studies have demonstrated that on removal from the freezer, one can store the undiluted vaccine for up to 31 days at 2 degrees -8 degrees C before use.

The statement said Pfizer's covid19 vaccine won WHO emergency use listing (EUL) certification in December 2020.

"Since then, the manufacturer has submitted data to the 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 keenly promoted transparency of the conditions approved so that practitioners and populations know about changes made on the basis of data available.

The statement said WHO and other agencies extended the vaccine's shelf life based on data assessing the vaccine's "quality attributes, physical appearance, and potency." It cited Pombo as saying quality interventions would protect the integrity of the vaccines.

"Health practitioners and the immunisation programme 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 covid19 vaccines and the process for approval."

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