COVID-19 vaccines efficacy in preventing or limiting SARS-CoV-2 infections

We used data from the nationwide COVID-19 vaccination campaign to assess to which extent COVID-19 vaccines may be effective for preventing newly diagnosed SARS-CoV-2 infections in the general Italian population. Compared to unvaccinated people, these figures translated into a cumulatively lower risk of SARS-CoV-2 infection of 68% (OR, 0.32; 95%CI, 0.19-0.56) in the entire cohort of COVID-19 vaccine recipients, with such risk reduction being the highest in those who received the vaccine booster dose (OR, 0.14; 95%CI, 0.14-0.14), followed by those who completed the primary vaccination within 120 days (OR, 0.29; 95%CI, 0.29-0.29) and, finally, by those who had completed the primary vaccination cycle by over 120 days (OR, 0.40; 95%CI, 0.40-0.40). The results of this analysis on available data of the ongoing nationwide Italian COVID-19 vaccination campaign suggest that although the viral load may be basically similar between unvaccinated subjects with primary SARS-CoV-2 infection and vaccinated people with breakthrough infections, the overall risk of being infected by SARS-CoV-2 is nearly 70% lower in vaccine recipients.