Answer given by Ms Kyriakides on behalf of the European Commission
It is not uncommon that for newly authorised medicines the shelf life of a product will be extended at the request of the marketing authorisation holder based on additional stability data that were not yet available at the time of the initial marketing authorisation.
The European Medicines Agency (EMA) reviews the data and can recommend updating the product information. The Commission, following regulatory scrutiny of EMA’s recommendation, will then amend the marketing authorisation.
In the case of the COVID-19 vaccine Comirnaty, the shelf life approved with the initial marketing authorisation was 6 months at ‐90 to ‐60 degrees Celsius. On 23 September 2021, following the EMA assessment of additional data submitted by the company, the shelf life was extended to 9 months when stored at ‐90 to ‐60 degrees Celsius.
Within the 9 months shelf life, unopened vials can be stored at ‐25 to ‐15 degrees Celsius for a single period of up to 2 weeks, and then can be returned to ‐90 to ‐60 degrees Celsius.
From a scientific point of view, EMA concluded that the new 9 months shelf life could apply to already released batches of Comirnaty, provided that the approved storage conditions had been guaranteed throughout the supply chain and an agreement had been made with relevant national authorities.
This conclusion was based on the fact that the extended shelf-life did not result from a change in the formulation of the product, but additional stability data.
-  Information on the data that informed the approved shelf-life of Comirnaty can be found in the assessment report for the initial approval: https://www.ema.europa.eu/en/documents/assessment-report/comirnaty-epar-public-assessment-report_en.pdf
-  Information regarding the shelf life and storage for Comirnaty can be found in Section 6 of Annex I of the product information: https://ec.europa.eu/health/documents/community-register/html/h1528.htm