Influence of COVID-19 mRNA vaccination on the efficacy and safety of Botulinum toxin type A injections.

[BACKGROUND] Concerns have been raised recently regarding the efficacy and safety of Botulinum toxin type A (BTA) injections following COVID-19 vaccination.

[AIMS] To assess the influence of BNT162b2 mRNA vaccine on the safety and efficacy of BTA injections performed for aesthetic indications.

[METHODS] A retrospective cohort study followed patients undergoing periodic BTA treatments who completed two doses of BNT162b2 vaccine. The latency between BTA injections before and after getting vaccinated was assessed for all study participants. Efficacy and longevity of BTA was reflected and evaluated by the latency between BTA injections. Patients were longitudinally monitored for the development of adverse events.

[RESULTS] Forty-five patients were eligible for inclusion in the current study. The mean (standard deviation [SD]) age of patients was 48.3 (8.9) years and 40 (88.9%) patients were females. The mean (SD) number of pre- and post-COVID-19 vaccination BTA injections was 5.1 (2.6) and 3.1 (0.4), respectively. The average (SD) interval between BTA injections after COVID-19 vaccination (96.0 [12.3] days) was significantly shorter than before it (118.6 [22.7]; p < 0.001). No severe BTA-associated adverse events were registered after the administration of BNT162b2 vaccine.

[CONCLUSIONS] Our findings indicate that BTA might be less effective after COVID-19 vaccination. Further research is required to delineate the pathomechanism underlying this observation.