Because the expiration date of Pfizer vaccines has been extended

Because the expiration date of Pfizer vaccines has been extended

From 6 to 9 months, as long as the vaccine is stored in the correct cold conditions. Here are the cases in which attention should be paid to the date shown on the label

(photo: Man Napo / Unsplash) The issue of the conservation and shelf life of anti Covid-19 vaccines has arisen since the autumn of 2020, as soon as it became clear that vaccine formulations were on the way that required very special cold conditions. And if almost a year later - and with the summer behind us - we can now say that the challenge of the logistics supply chain in our country has been solved without particular critical issues, in recent months the theme of the end of life of the unused doses. A topic that concerns, on the one hand, discontinued vaccines, such as those with viral vectors by AstraZeneca and Johnson & Johnson, which makes more sense to redistribute abroad than to throw in the trash, but on the other hand also the most used rna formulations messenger of Pfizer and Moderna.

For the latter, in fact, the question is twofold: first of all the evidence on the effective stability of the vaccine compound is consolidating, therefore it is possible to calibrate the expiration date on the basis of real data and not just by analogy with other similar compounds. And then a good number of close-to-maturity doses are starting to accumulate in the refrigerator-freezers, given that the vaccine supplies have reached full capacity and, indeed, we have more doses at home than we actually need.

Pfizer's Comirnaty goes from 6 to 9 months

The news, which at least for Italy is this week, is that it has been established that the Comirnaty vaccine - the one developed by Pfizer and Biontech, so to speak - from now on it will last longer. The period of validity has been extended from the previous 6 to the current 9 months, obviously provided that the conservation takes place correctly in the manner provided and without interrupting the cold chain.

In particular, the expiry extension is valid for unopened vials and which are always stored at a temperature between -90 ° C and -60 ° C, with the exception of a maximum period of two weeks in which the storage temperature may be higher, ta -25 ° C and -15 ° C. And obviously all the indications on the (very short) useful life once removed from the freezers and stored at room temperature remain valid.

The decision chain

As you can imagine, the decision to lengthen the useful life of the Pfizer vaccine for Italy is not an exclusively local initiative. The first officialization, which acted as the leader at a global level, was that of the US Food and Drug Administration, which had already formally communicated the new duration of the validity of the vials on 23 August. For Europe, the European Medicines Agency (Ema) officially started the evaluations on 10 September, and then concluded them on the 23rd of the same month with an update of section 6.3 of the package leaflet, in which the deadline was extended by analogy. from 6 to 9 months.

Subsequently, Pfizer itself has distributed the information to all member countries of the European Union (document of 27 September), and the update was also formally accepted by our Italian Medicines Agency (Aifa) Monday 4 October. Consequently, the wording on both the Summary of Product Characteristics (Rcp) and the package insert will be updated.

Although none of these documents explicitly mention the reasons and scientific evidence behind this decision, it seems evident that - given that more than 9 months have actually passed since the first doses were marketed - we can now have direct information on the stability of the vaccine compounds. It is therefore a decision based on evidence, and not on abstract hypotheses or forecasts, and the initial choice of setting the validity at only 6 months (dictated by prudence) was overcome by the good news of being able to count on 3 months in more, at least, of validity.

How to read the expiration dates

First of all, a small clarification: vaccines do not indicate an expiration date with day, month and year, but only the month and year, meaning the last day of the month as the term of validity.

Naturally, the ongoing modification of the duration of validity slightly complicates communication during the transitional period. That is to say, there are packages of vaccines in circulation that have the old expiration date on the label, 3 months earlier than the one currently established. The situation can be summarized in 3 cases.

First, the vaccines produced until February 2021, i.e. with a maximum expiry date of August 2021: these vaccines are formally expired before the extension took effect, therefore in theory (assuming that there were still in circulation and that they had not already been exhausted) should have been eliminated at the time of expiration.

The second case is that of vaccines that are close to expiry, for which it is reported the old date on the label, to which 3 months of validity must now be added. As specified, in fact, updating the shelf life of vaccines also has retroactive value, provided that the doses had not already expired at the time of the decision. The first lots to fall into this category are those expiring in September 2021, which is extended to December 2021. Thus October 2021 becomes January 2022, November 2021 becomes February 2022, and so on up to lots with expiry in March 2022 (therefore produced in September 2021), which are extended to June 2022.

Finally, the third case is that of vaccines produced from now on, i.e. from October 2021 onwards, which will already carry the expiration date on the label calculated on 9 months instead of 6. So, when an expiration date from July 2022 onwards will be found on the label, that date will already be the correct one and no more months will be added.

The expirations of the other vaccines do not change

In the case of Moderna's Spikevax vaccine, for Europe the EMA currently has confirmed a duration of validity equal to 7 months, always provided that the vaccine is stored in conditions of low temperatures (between -25 ° C and -15 ° C, in this case). In this case there are no extensions or variations in the duration of the doses, just as also for the viral vector formulations.

For the avoidance of doubt, the duration of the useful life of the vaccine doses stored in the cold has nothing to what to do with the duration of the protection period offered by the vaccine, nor with bureaucratic timing such as the duration of the green pass or other.

Although interesting from the point of view of the process, in fact, this novelty relating to the Pfizer vaccine impacts only on the logistic management chain of doses, trusting (and there is no reason to doubt it at the moment) that only doses that at that moment are within the validity period are administered. And, again within this time window, there is no evidence of variations in the efficacy of the vaccine depending on when it is used, as long as the deadline is not exceeded.

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