Back to Search Start Over

Surveillance of Severe Acute Respiratory Infection and Influenza Vaccine Effectiveness among Hospitalized Italian Adults, 2021/22 Season

Authors :
Donatella Panatto
Alexander Domnich
Maria Chironna
Daniela Loconsole
Christian Napoli
Alessandra Torsello
Ilaria Manini
Emanuele Montomoli
Elena Pariani
Silvana Castaldi
Andrea Orsi
Giancarlo Icardi
on behalf of the IT-BIVE-HOSP Network Study Group
Source :
Vaccines, Vol 11, Iss 1, p 83 (2022)
Publication Year :
2022
Publisher :
MDPI AG, 2022.

Abstract

Following an extremely low incidence of influenza during the first waves of the ongoing COVID-19 pandemic, the 2021/22 Northern Hemisphere winter season saw a resurgence of influenza virus circulation. The aim of this study was to describe epidemiology of severe acute respiratory infections (SARIs) among Italian adults and estimate the 2021/22 season influenza vaccine effectiveness. For this purpose, a test-negative case-control study was conducted in a geographically representative sample of Italian hospitals. Of 753 SARI patients analyzed, 2.5% (N = 19) tested positive for influenza, most of which belonged to the A(H3N2) subtype. Phylogenetic analysis showed that these belonged to the subclade 3C.2a1b.2a.2, which was antigenically different from the 2021/22 A(H3N2) vaccine component. Most (89.5%) cases were registered among non-vaccinated individuals, suggesting a protective effect of influenza vaccination. Due to a limited number of cases, vaccine effectiveness estimated through the Firth’s penalized logistic regression was highly imprecise, being 83.4% (95% CI: 25.8–97.4%) and 83.1% (95% CI: 22.2–97.3%) against any influenza type A and A(H3N2), respectively. Exclusion of SARS-CoV-2-positive controls from the model did not significantly change the base-case estimates. Within the study limitations, influenza vaccination appeared to be effective against laboratory-confirmed SARI.

Details

Language :
English
ISSN :
2076393X
Volume :
11
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Vaccines
Publication Type :
Academic Journal
Accession number :
edsdoj.3a25990b16324cc183fe51d809d319db
Document Type :
article
Full Text :
https://doi.org/10.3390/vaccines11010083