Inadvertent post-expiry COVID-19 vaccination in 282 seniors: Safety, efficacy, and implications for extended off-label stability data.

Abstract

Objectives: To describe safety and clinical outcomes after inadvertent post-expiry administration of Pfizer-BioNTech SARS-CoV-2 vaccine to adults aged ≥80 years in Swedish primary care; indicate what can (and cannot) be inferred about efficacy from real-world follow-up; and identify system needs for clearer expiry labelling and producer-led, longer-horizon post-expiry evidence. The study was not designed to estimate vaccine effectiveness.

Study design: Service evaluation; observational single-arm cohort (ambispective).

Methods: After discovery that 282 recipients had received doses 3-5 months past the labelled expiry, 280 survivors were informed and offered in-date revaccination within ∼4 weeks. Clinicians recorded revaccination uptake, adverse events exceeding expected post-mRNA symptoms after expired and (if applicable) in-date doses, and any confirmed/strongly suspected COVID-19 prior to revaccination; deaths were attributed via records. A change in manufacturer presentation of shortened/altered expiry encountered locally at point of care was documented.

Results: 208/280 accepted revaccination; 72/280 declined. Two deaths occurred from age-related/pre-existing illness (not vaccination-related). No serious or unexpected adverse events were recorded after expired or in-date doses. A small number reported mild, self-limited illness compatible with COVID-19; there were no hospitalisations and no laboratory-confirmed cases.

Conclusions: In this cohort of older seniors, inadvertent post-expiry vaccination was followed by no safety signal and no COVID-19 hospitalisations; effectiveness cannot be quantified from this design. Given recurring human error and cold-chain stress, clearer expiry labelling and transparent, real-life post-expiry stability/efficacy data (weeks-months; including temperature-excursion profiles) are needed to support patient safety, reduce wastage, and strengthen preparedness.