*2.1. Study Design*

The cross-sectional study was conducted from 15th July 2020 to 15th August 2020. The online survey was developed using Google Forms and included three main sections: socio-demographic characteristics, 15D instrument and perception towards COVID-19 vaccination (Supplementary file\_Questionnaire). The online survey was anonymous and confidential. As dissemination channels, we used pharmacist groups from social media, such as Facebook, and emails to our former students.

The socio-demographic section was composed of items exploring age, gender, marital status, experience as a pharmacist, income working as a pharmacist, and pharmacy specialization. Monthly income working as a pharmacist was stratified into low (less than 600 Euro), medium (600–1000 Euro), or high (more than 1000 Euro).

The second section of the questionnaire assessed the HRQoL using the 15D instrument [27,28]. The 15D questionnaire comprises 15 dimensions (mobility, vision, hearing, breathing, sleeping, eating, speech, excretion, usual activities, mental function, discomfort and symptoms, depression, distress, vitality, and sexual activity), with each dimension being divided into five levels that range from no problems to severe difficulties. The single index score (15D score), representing the overall HRQoL on a 0–1 scale (1 = full health, 0 = being dead) and the dimension level values, reflecting the goodness of the levels relative to no problems on the dimension (=1) and to being dead (=0), are calculated from the questionnaire by using a set of population-based preference or utility weights.

The third section included five items specifically developed for the purpose of the study, which were related to vitamin C or D supplementation (self or recommended to others) during the COVID-19 pandemic and to vaccination against COVID-19.
