@misc{isabelle_boutron_2021_5511936, author = {Isabelle Boutron and Anna Chaimani}, title = {{Protocol effectiveness of COVID-19 vaccines on variant of concern. A systematic review of observational studies}}, month = sep, year = 2021, publisher = {Zenodo}, version = {V2 31-8-2021}, doi = {10.5281/zenodo.5511936}, url = {https://doi.org/10.5281/zenodo.5511936} }