Batch-Dependent Safety Signal: Nationwide Analysis of Suspected Adverse Events Following COVID-19 Vaccination in Germany

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 1 000 administered vaccine doses. Results: SAE rates ranged between 2.2 and 22.8 per 1 000 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 1 000 doses of Comirnaty, Spikevax, and Vaxzevria, respectively, but fell to 4.4, 11.6, and 7.4 per 1 000 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.