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Review
. 2023 May 22;11(5):1011.
doi: 10.3390/vaccines11051011.

The Impact of Vaccination on COVID-19 Burden of Disease in the Adult and Elderly Population: A Systematic Review of Italian Evidence

Giovanna Elisa Calabrò  1   2 , Ciro Pappalardo  1 , Floriana D'Ambrosio  1 , Michele Vece  3 , Chiara Lupi  3 , Alberto Lontano  1 , Mattia Di Russo  1 , Roberto Ricciardi  2 , Chiara de Waure  3
Affiliations
Review

The Impact of Vaccination on COVID-19 Burden of Disease in the Adult and Elderly Population: A Systematic Review of Italian Evidence

Giovanna Elisa Calabrò et al. Vaccines (Basel). .

Abstract

COVID-19 is a major global health threat, with millions of confirmed cases and deaths worldwide. Containment and mitigation strategies, including vaccination, have been implemented to reduce transmission and protect the population. We conducted two systematic reviews to collect nonrandomized studies investigating the effects of vaccination on COVID-19-related complications and deaths in the Italian population. We considered studies conducted in Italian settings and written in English that contained data on the effects of vaccination on COVID-19-related mortality and complications. We excluded studies that pertained to the pediatric population. In total, we included 10 unique studies in our two systematic reviews. The results showed that fully vaccinated individuals had a lower risk of death, severe symptoms, and hospitalization compared to unvaccinated individuals. The review also looked at the impact of vaccination on post-COVID-19 syndrome, the effectiveness of booster doses in older individuals, and nationwide adverse events. Our work highlights the crucial role that vaccination campaigns have played in reducing the burden of COVID-19 disease in the Italian adult population, positively impacting the pandemic trajectory in Italy.

Keywords: COVID-19; SARS-CoV-2; adult population; complications; elderly people; hospitalization; lethality; mortality; vaccination; vaccines.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Included studies’ periods and areas. This figure shows the timeline and area of included studies from March 2020 to January 2022 [42,43,44,45,46,47,48,49,50,51], with the beginning of the vaccination campaign marked by a solid line, the one on the left dividing the first and second waves, and the transition from the Alpha/Delta variants to the Omicron variant marked by a line on the right. Overlapping studies were present in the two systematic reviews, resulting in a total of 10 unique studies. Among the total of 10 unique studies, the author names and publication years are in bold for studies on the impact of vaccination on COVID-19 deaths exclusively included in the review and italicized for studies on the impact of vaccinations on COVID-19-related complications exclusively included in the review.
Figure 2
Figure 2
PRISMA flowchart for the systematic review of the impact of vaccinations on COVID-19-related mortality.
Figure 3
Figure 3
PRISMA flowchart for the systematic review of the impact of vaccinations on COVID-19-related complications.
See this image and copyright information in PMC

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