Comparative tolerability profile of mRNA vaccines during mass vaccination of healthcare professionals at a tertiary hospital. An active pharmacovigilance study

ABSTRACT

Background: Further understanding on the safety profile of vaccines in a real-world still need to be elucidated, such as the comparative tolerability and reactogenicity of mRNA vaccines (BNT162b2 and MRNA- 1273) beyond the controlled context of clinical trials. An active pharmacovigilance study was designed to capture a complete short-term safety profile of two mRNA vaccines BNT162b2 and mRNA- 1273, targeting incidence rates of adverse reactions within a pre-defined denominator of vaccinated healthcare professionals. Methods: A prospective active surveillance study was implemented during the vaccination campaign at Hospital Clínic by a multidisciplinary team, involving the Pharmacovigilance Technical Committee, the Department of Preventive Medicine and Epidemiology and the Department of Occupational Health Care of the Hospital. Target population of the program included vaccinated professionals from Hospital Clínic and affiliated institutions, who were vaccinated with BNT162b2 and mRNA-1273. The program was based on the delivery of a structured questionnaire by telephonic interview after each vaccine dose. A total of 64% of vaccinated professionals completed the questionnaire (n=5088). Results: A total of 85% subjects suffered at least 1 AR reaction with the vaccine. The proportion of professionals developing any AR was 2878 (81.2%) after vaccination with BNT162b2 and 1463 (92.9%) after vaccination with mRNA-1273. Severe ARs (VAS scoring ≥ 7) were reported in 1184 (33.7%) professionals after vaccination with BNT162b2 and 886 (56.4%) after mRNA-1273. In the multivariate analysis, mRNA-1273 showed a greater reactogenicity than BNT162b2 (OR=3.04 (95% CI 2.48 - 3.73;p-value <0.0001)). Conclusions: Our study shows that mRNA-1273 has greater reactogenicity than BNT162b2. Overall, both mRNA vaccines had a reasonable tolerability profile, compared in a real-world scenario. This can be understood as a reassuring message for the medical and scientific community.