The emergence of the COVID-19 pandemic in early 2020 led countries to implement a set of public health and social measures (PHSMs) attempting to contain the spread of the SARS-CoV-2 virus. This study reviewed existing literature to identify the PHSMs considered to have most impacted the epidemiological curve of COVID-19 during different stages of the pandemic. The PHSM under study were selected from the Oxford COVID-19 Government Response Tracker, supplemented by topics presented during the Rapid Exchange Forum meetings in scope of the Population Health Information Research Infrastructure (PHIRI) project, and were analysed using Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. In addition, two Modified Delphi Panel surveys were conducted among subject matter experts from 30 European countries. The measures with clearest evidence on their positive impact from the evidence-based review include social distancing, hygiene measures, mask measures and testing policies. From the Modified Delphi Panel, the PHSMs considered most significant in the four periods analysed were case isolation at home, face coverings, testing policy, and social distancing, respectively. The results of the study, drawn from both the available scientific evidence and the subjective perspectives of relevant subject matter experts, illustrate lessons learned for future pan- and epidemics and serve as a contribution to the health systems resilience discussion.