Deciphering deaths associated with severe serious adverse events following SARS-CoV-2 vaccination: A retrospective cohort study

"Discussion: We performed a retrospective cohort study involving 687 cases of reported severe SAEs that resulted in significant morbidity or mortality following SARS-CoV-2 vaccination. The key findings of this study were as follows: among patients with severe SAEs [serious adverse events], (1) the viral vector-based vaccines were associated with a lower risk of mortality than the mRNA-based vaccines; (2) vaccinations performed at nursing hospitals and facilities were associated with a higher risk of mortality, whereas vaccinations performed at government-supported vaccination centers were associated with a lower risk; (3) age, but not CCI [Charlson comorbidity index], was associated with a slightly increased risk of mortality; and (4) the CFR [case fatality rate] was variable according to different etiologies of severe SAEs, and an apparent mismatch was found between the frequency and CFRs. We believe our study is the first to provide a comprehensive insight into the fatality rate of individual AE etiologies and the potential risk factors for mortality in patients with severe SAEs following SARS-CoV-2 vaccination ...

Diseases of the circulatory system were the most common causes of severe SAEs with fatal outcomes. However, the CFR of this category was lower than anticipated (39.1 %), implying that diseases of the circulatory system were monitored and treated relatively well. This may be due to the acuteness of symptoms and the reputation built through media exposure. The most critical severe SAE with a fatal outcome in our study was neoplasms, which had a CFR of 85.7 %. The most commonly reported neoplasm was acute myeloid leukemia ...

Finally, 86 patients with unidentifiable diagnoses died within 42 days from the last vaccination in our study, and the diagnoses were inconclusive in 17 patients, even with autopsies. These patients experienced sudden death due to unclear causes and were labelled arbitrarily with sudden cardiac death, acute respiratory failure, or unclassified ...

In conclusion, we found that older people receiving mRNA-based vaccines in nursing hospitals and facilities who reportedly develop severe SAEs with a high CFR (e.g., neoplastic, respiratory, and digestive disorders) may have an increased risk of 42-day mortality."