The additional dose of the Covid-19 vaccine protects 82% from severe disease.
This was indicated by the Istituto Superiore di Sanità (Iss) in its weekly report on "Covid-19, surveillance, impact of infections and vaccination efficacy".
It also appears that with the full course (two doses), the effectiveness of the vaccine in preventing severe disease is 62.5% in those vaccinated with less than 90 days, 64% in those vaccinated between 91 and 120 days and 69 % over 120 days.