Spontaneous reporting of adverse reactions associated with the COVID-19 vaccine in health care professionals: A descriptive observational study conducted in a Portuguese hospital.

Background: The coronavirus disease 2019 (COVID-19) was classified as a pandemic in March 2020 by the World Health Organization. The Pfizer-BioNTech COVID-19 vaccine was the first to be authorized in the European Union, based on data from phase 1, 2, and 3 clinical trials of limited duration. Concerns have been raised regarding the vaccine's safety profile.