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Safety of BNT162b2 mRNA COVID-19 Vaccine Batches: A Nationwide Cohort Study
Anders Hviid1,2, Ingrid Bech Svalgaard1
1Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
Objectives:
The safety of the BNT162b2 mRNA COVID-19 vaccine has been extensively evaluated since the global rollout began. While serious adverse events are rare, safety issues continue to arise. This study evaluates the claim that earlier small vaccine batches were associated with higher rates of serious adverse events compared to later batches.
Design, Participants, Setting:
A nationwide cohort study was conducted in Denmark, comprising individuals vaccinated with the BNT162b2 vaccine from 52 pre-defined batches classified into three pre-defined groups. Vaccinated individuals were matched 1:1 between batch groups on age, sex, and vaccination priority group. The study outcomes included 27 serious adverse events, two negative control outcomes, and all-cause mortality. Cox regression was used to estimate hazard ratios (HRs) comparing rates between batch groups in the 28 days following vaccination. We conducted two comparisons of the early small batches to two groups of larger batches used later in the pandemic.
Results:
In the study period, 9 983 728 vaccinations were administered from batches in the three pre-defined groups. Slightly increased rates of arrhythmia were observed in both study comparisons, HRs 1.25 (95% CI, 1.05-1.50) and 1.15 (1.00-1.31), respectively, but sensitivity analyses did not robustly support these associations. For the remaining outcomes, increased rates in both study comparisons were not observed.
Conclusion:
This nationwide cohort study provides reassurance regarding the safety of the BNT162b2 vaccine across different batches used in Denmark. The findings support the overall safety of the vaccine, with no clinically relevant variations in serious adverse event rates between batches.
Insights
This study found no significant safety concerns with the BNT162b2 mRNA COVID-19 vaccine batches used in Denmark. Analysis of millions of vaccinations showed no clinically relevant differences in serious adverse events between early and later vaccine batches.
Area of Science:
- Vaccinology
- Immunology
- Public Health
Background:
- The BNT162b2 mRNA COVID-19 vaccine's safety is crucial for public trust and vaccine uptake.
- Concerns have been raised about potential variations in vaccine safety profiles across different manufacturing batches.
- Previous studies have extensively evaluated the vaccine's safety, but batch-specific comparisons are less common.
Purpose of the Study:
- To investigate whether earlier, smaller batches of the BNT162b2 vaccine were associated with higher rates of serious adverse events compared to later, larger batches.
- To provide data-driven reassurance regarding the safety of the BNT162b2 vaccine across its manufacturing lifecycle.
- To assess the association between BNT162b2 vaccine batches and serious adverse events, including specific outcomes and all-cause mortality.
Main Methods:
- A nationwide cohort study in Denmark involving individuals vaccinated with BNT162b2.
- Vaccine batches were categorized into three groups, with early small batches compared to later larger batches.
- Cox regression analysis was used to compare rates of 27 serious adverse events and all-cause mortality within 28 days post-vaccination, with 1:1 matching for key demographic factors.
Main Results:
- Over 9.9 million BNT162b2 vaccinations were analyzed across the defined batch groups.
- Slightly increased rates of arrhythmia were observed in comparisons involving early batches, but these findings were not robustly supported by sensitivity analyses.
- No increased rates of other serious adverse events or all-cause mortality were detected when comparing early small batches to later larger batches.
Conclusions:
- The study provides strong reassurance for the safety of the BNT162b2 mRNA COVID-19 vaccine across various batches used in Denmark.
- No clinically significant variations in serious adverse event rates were identified between different vaccine batches.
- The findings support the overall safety profile of the BNT162b2 vaccine, irrespective of batch manufacturing differences.
