By Sola Ogundipe
The World Health Organisation, WHO Regional Office for Africa has clarified the issue of expiry dates of COVID-19 vaccines in general, and specifically on AstraZeneca vaccine doses produced by the Serum Institute of India, SII, also known as Covishield.
According to WHO, vaccines, like all other medicinal products, come with a date of expiry and shelf-life determined by the manufacturer and approved by regulatory authorities.
Given the urgency of the COVID-19 pandemic, initial emergency use authorization on a number of COVID-19 vaccines, including the AstraZeneca Covishield vaccine was given by regulators when only six months’ worth of data for assignment of the expiration date was available.
For an extension to the shelf-life of COVID-19 vaccines that have received WHO Emergency Use Listing (EUL), the data from manufacturers will be reviewed and the outcomes disseminated to all country’s national regulatory authorities for their decision-making.
National regulatory authorities oversee all post approval changes to COVID-19 vaccines including any changes to their shelf-life and expiry dates in their countries. Since reliance on EUL has been a crucial factor in the national authorisation of COVID-19 vaccines, national regulatory authorities can make decisions based on the EUL assessment of stability data from the vaccine manufacturer and recommended shelf-life.
Shelf life & expiry of Covishield vaccine
In March, the African Union’s African Vaccine Acquisition Task Team (AVATT) redistributed 925,000 doses of Covishield vaccine produced by SII to 13 African countries with an expiry date of 13 April 2021.
The bulk of the vaccine doses were administered, but some countries have unused doses remaining.
Who stresses that any vaccine that has passed its expiry date, including Covishield, should not be administered.
While discarding vaccines is deeply regrettable in the context of any immunisation programme, WHO recommends that these expired doses should be removed from the distribution chain and safely disposed of.
The shelf-life of a vaccine is a reflection of how long the vaccine retains its potency and stability at a given storage temperature and therefore its effectiveness.
The shelf-life is used to establish the expiry date of each batch of the vaccine product. Expiry dates do not affect the safety of the vaccine, rather are related to the potency or amount of protection the vaccine gives.
The WHO prequalification team is expecting to receive additional stability data for Covishield from SII. This data enables WHO to do a rigorous review and approve any proposed extension to the vaccine shelf-life.
According to WHO, any extension in the shelf-life will only apply to vaccines not yet labelled and distributed. Therefore, the expired or near-to-expire doses in distribution for use will not be affected by the future decision of shelf-life extension.
This decision is expected to be communicated to all countries’ national regulatory authorities in due course.
Safe disposal of expired COVID-19 vaccines
There is no special procedure applied for disposing of COVID-19 vaccines. The disposal should follow the existing national guidelines for the safe disposal of vaccines.
If a standard protocol does not exist, countries are to refer to the WHO Guidelines for the Safe Disposal of Unwanted Pharmaceuticals In and After an Emergency.
The WHO says immunisation programmes should support health workers with information about the verification and disposal of expired doses.
Broader public communications may also be required to reassure that expiry date issues are more about vaccine potency and performance and are not a safety issue.
Tracking expiry dates
Synchronising vaccination campaigns with the shelf-life of a vaccine at the time of its arrival in a country is key to facilitating consumption of the supply before they expire.