Moderate influenza vaccine effectiveness against A(H1N1)pdm09 virus, and low effectiveness against A(H3N2) subtype, 2018/19 season in Italy.

Autor: Bellino, Stefania, Bella, Antonino, Puzelli, Simona, Di Martino, Angela, Facchini, Marzia, Punzo, Ornella, Pezzotti, Patrizio, Castrucci, Maria Rita, the InfluNet Study Group
Předmět:
Zdroj: Expert Review of Vaccines; Nov2019, Vol. 18 Issue 11, p1201-1209, 9p
Abstrakt: Background: Influenza vaccines are updated every year to match the vaccine strains with currently circulating viruses; consequently influenza vaccine effectiveness (IVE) has to be assessed annually. Research design and methods: A test-negative case-control study was conducted within the context of the Italian sentinel influenza surveillance network to estimate IVE by age group, virus subtype, and vaccine brand in medically attended laboratory-confirmed influenza. Results: In Italy, the 2018/19 influenza season was characterized by the co-circulation of influenza A(H1N1)pdm09 and A(H3N2) viruses. The adjusted IVE estimate in preventing influenza was moderate (44.8%, 95% CI: 18.8 to 62.5) against A(H1N1)pdm09, whereas there was no evidence of effectiveness (1.8%, 95% CI: −37.8 to 30.1) in persons affected by A(H3N2). IVE against A(H1N1)pdm09 decreased with age ranging from 65.7% to 13.1% among children/adolescents and elderly, respectively; moreover results suggest that Vaxigrip Tetra® was more effective against A(H1N1)pdm09 compared to Fluarix Tetra® [62.5% (95% CI: 34.3 to 78.6) vs 24.5% (95% CI: −40.6 to 59.6)]. Low effectiveness (35.2%, 95% CI: −50.8 to 72.1) against A(H3N2) was detected only in the elderly immunized with Fluad®. Conclusions: Findings suggest that influenza vaccines were low to moderately effective, probably due to a mismatch between circulating and vaccine strains. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index