Batch-dependent safety signal: Nationwide analysis of suspected adverse events following COVID-19 vaccination in Germany

Abstract

Background

Preliminary reports have suggested a batch-dependent safety signal for COVID-19 vaccines. It is important to establish if these findings can be replicated.

Methods

We used publicly available nationwide data from Germany spanning the first 3.5 years of the vaccination campaign to calculate weekly rates of spontaneously reported suspected adverse events (SAEs) per 1000 administered vaccine doses.

Results

SAE rates ranged between 2.2 and 22.8 per 1000 doses and women accounted for 72% of all SAEs. Crucially, SAE rates for Comirnaty (Pfizer-BioNTech), Spikevax (Moderna), and Vaxzevria (AstraZeneca) were very high in the initial phase of vaccination rollout and hereafter declined precipitously. For example, SAE rates in weeks 1–4 of 2021 were 8.2, 50.8, and 620.9 per 1000 doses of Comirnaty, Spikevax, and Vaxzevria, respectively, but fell to 4.4, 11.6, and 7.4 per 1000 doses in weeks 12–16 of 2021.

Conclusions

SAE rates in Germany were highly elevated in the initial phase of COVID-19 vaccination rollout and then fell precipitously, a pattern compatible with a batch-dependent safety signal. Furthermore, there was a considerable overrepresentation of women with SAEs. These preliminary results call for more definitive studies of batch-dependent COVID-19 vaccine safety.