Health workers administer a Pfizer COVID-19 vaccine booster shot at the COVID-19 vaccination hub of San Giovanni Addolorata hospital, in Rome, Italy, 21 November 2021. ANSA/GIUSEPPE LAMI Health workers administer a Pfizer COVID-19 vaccine booster shot at the COVID-19 vaccination hub of San Giovanni Addolorata hospital, in Rome, Italy, 21 November 2021. ANSA/GIUSEPPE LAMI