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. 2021 Jun;26(25):2100507.
doi: 10.2807/1560-7917.ES.2021.26.25.2100507.

Risk of SARS-CoV-2 infection and subsequent hospital admission and death at different time intervals since first dose of COVID-19 vaccine administration, Italy, 27 December 2020 to mid-April 2021

Alberto Mateo-Urdiales  1   2 , Stefania Spila Alegiani  3 , Massimo Fabiani  1 , Patrizio Pezzotti  1 , Antonietta Filia  1 , Marco Massari  3 , Flavia Riccardo  1 , Marco Tallon  4 , Valeria Proietti  5 , Martina Del Manso  1   2 , Maria Puopolo  6 , Matteo Spuri  1 , Cristina Morciano  7 , Fortunato Paolo D'Ancona  1 , Roberto Da Cas  3 , Serena Battilomo  5 , Antonino Bella  1 , Francesca Menniti-Ippolito  3 ; Italian Integrated Surveillance of COVID-19 study group  8 ; on behalf of the Italian COVID-19 vaccines registry  8
Affiliations

Risk of SARS-CoV-2 infection and subsequent hospital admission and death at different time intervals since first dose of COVID-19 vaccine administration, Italy, 27 December 2020 to mid-April 2021

Alberto Mateo-Urdiales et al. Euro Surveill. 2021 Jun.

Abstract

To assess the real-world impact of vaccines on COVID-19 related outcomes, we analysed data from over 7 million recipients of at least one COVID-19 vaccine dose in Italy. Taking 0-14 days post-first dose as reference, the SARS-CoV-2 infection risk subsequently decreased, reaching a reduction by 78% (incidence rate ratios (IRR): 0.22; 95% CI: 0.21-0.24) 43-49 days post-first dose. Similarly, hospitalisation and death risks decreased, with 89% (IRR: 0.11; 95% CI: 0.09-0.15) and 93% (IRR: 0.07; 95% CI: 0.04-0.11) reductions 36-42 days post-first dose. Our results support ongoing vaccination campaigns.

Keywords: COVID-19; Italy; pandemic; vaccination.

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Conflict of interest statement

Conflict of interest: None declared.

Figures

Figure 1
Figure 1
Timeline since the start of the vaccination campaigna with the periods of selection and event ascertainment in the study population, Italy, 27 December 2020–2 May 2021
Figure 2
Figure 2
Adjusted incidence rate ratios with 95% confidence intervals of SARS-CoV-2 (A) infection, (B) hospitalisation and (C) death, by 7-day period with respect to the first 14 days post first-dose of COVID-19 vaccine, Italy, 27 December 2020–18 April 2021
Figure 3
Figure 3
Adjusted incidence rate ratios with 95% confidence intervals of SARS-CoV-2 infection in (A) healthcare workers, (B) residents of long-term care facilities and (C–F) age groups, by 7-day period with respect to the first 14 days post first-dose of COVID-19 vaccine, Italy, 27 December 2020–18 April 2021
See this image and copyright information in PMC

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