2.2. Data extraction

A tabulated form was prepared for data extraction. Data extraction was performed by two reviewers (A.P. and G.F) using a pre-designed Excel sheet, and every disagreement was resolved by discussion with the third reviewer (Y.AA.). The data reflecting surveyed participants’ attitudes to receiving future COVID-19 vaccines were sought and the following measurements were included: the rate of vaccination acceptance/rejection, the rate of positive/negative attitude (expressed as the rate of positive/negative responses to a specific set of questions related to vaccine uptake), the rate of people willing to enroll themselves/their child in a COVID-19 vaccine trial, the rate of participants willing to pay for the future vaccine. Other relevant information regarding multiple dimensions were collected for each study, including: (1) the first author and year of publication; (2) geographical context (city and/or country); (3) study design; (4) population of interest; (5) data collection method; (6) demographic characteristics; (7) motivators toward vaccine acceptance and uptake; (8) barriers against vaccine acceptance and uptake. After summarizing all the data in the tabular form, it was possible to identify all eligible studies (those reporting some of the parameters related to the uptake of future COVID-19 vaccine) as well as identify those that did not fulfill the inclusion criteria.