?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.au=Mills%2C+Melinda+C&rft.aufirst=Melinda+C&rft.aulast=Mills&rft.pages=e15-e22&rft.volume=7&rft.title=The+Lancet+Public+Health&rft.atitle=The+effect+of+mandatory+COVID-19+certificates+on+vaccine+uptake%3A+synthetic-control+modelling+of+six+countries&rft.issn=2468-2667&rft.issue=1&rft.date=January+2022&rft.genre=article