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.
Moderate influenza vaccine effectiveness against A(H1N1)pdm09 virus, and low effectiveness against A(H3N2) subtype, 2018/19 season in Italy / Bellino, Stefania; Bella, Antonino; Puzelli, Simona; Di Martino, Angela; Facchini, Marzia; Punzo, Ornella; Pezzotti, Patrizio; Rita Castrucci, Maria; Study Group: Giuseppina Di Mario, Influnet; Calzoletti, Laura; Fabiani, Concetta; Chironna, Maria; Germinario, Cinzia; Tramuto, Fabio; D’Alessandro, G.; Di Carlo, Vittorio; Affanni, Paola; Grazia Pascucci, Maria; D’Agaro, Pierlanfranco; Gallo, Tolinda; Pagani, Elisabetta; Natter, Bernhard; Camilloni, Barbara; Tosti, Anna; Pariani, Elena; Senatore, Sabrina; Serra Pierina Rita Tanchis Valeria Ghisetti, Caterina; Tiberti, Donatella; Romano, Lucio; Volpe, Enrico; Giannecchini, Simone; ., Emanuela Balocchini. - In: EXPERT REVIEW OF VACCINES. - ISSN 1744-8395. - 18:11(2019), pp. 1201-1209. [10.1080/14760584.2019.1688151]
Moderate influenza vaccine effectiveness against A(H1N1)pdm09 virus, and low effectiveness against A(H3N2) subtype, 2018/19 season in Italy
Paola Affanni;
2019-01-01
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
