Objective:

Continuous monitoring of COVID-19 vaccines safety may provide additional information to health care professionals and the general population. The aim of the present study was to analyze the local and systemic adverse events following the administration of the Spikevax® (Moderna) vaccine, and to identify the factors related to greater reactogenicity.

Method:

Using a telephone survey, we interviewed 331 recipient of the Spikevax® vaccine (50.2% men; Meanage = 46.4). Participants characteristics, prior COVID-19 infection and local and systemic adverse events within seven days following the first and second vaccine doses were asked.

Results:

Injection site pain, fatigue and headache were the most common adverse events. The prevalence and intensity of local events was higher after the first dose, while systemic events were higher in the second one. Most adverse events were mild/moderate; 1.2% of participants needed hospitalization or emergency room visit. Women and participants aged 18-55 years were more likely to experience greater reactogenicity, participants with prior COVID-19 infection had more systemic events after the first dose, and participants with chronic diseases other than hypertension reported fewer systemic adverse events following the second dose.

Conclusions:

Our results are consistent with previous studies, identifying women, people aged 18-55 years and those with previous COVID-19 infection as those who experienced the greatest reactogenicity to the vaccine. A relationship was also found between reactogenicity and suffering from a chronic disease other than hypertension.