Moderate Vaccine Effectiveness against Severe Acute Respiratory Infection Caused by A(H1N1)pdm09 Influenza Virus and No Effectiveness against A(H3N2) Influenza Virus in the 2018/2019 Season in Italy
oleh: Caterina Rizzo, Francesco Gesualdo, Daniela Loconsole, Elisabetta Pandolfi, Antonino Bella, Andrea Orsi, Giulia Guarona, Donatella Panatto, Giancarlo Icardi, Christian Napoli, Giovanni Battista Orsi, Ilaria Manini, Emanuele Montomoli, Ilaria Campagna, Luisa Russo, Valeria Alfonsi, Simona Puzelli, Antonino Reale, Umberto Raucci, Livia Piccioni, Carlo Concato, Marta Luisa Ciofi Degli Atti, Alberto Villani, Maria Chironna, Alberto Eugenio Tozzi
| Format: | Article |
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| Diterbitkan: | MDPI AG 2020-07-01 |
Deskripsi
Every season, circulating influenza viruses change; therefore, vaccines must be reformulated each year. We aimed to estimate vaccine effectiveness (VE) against severe influenza infection for the 2018/19 season in Italy. We conducted a test-negative design case-control study at five Italian hospitals. We estimated influenza VE against severe acute respiratory infection (SARI) requiring hospitalisation overall, and by virus subtype, vaccine brand, and age. The 2018/19 season was characterised by A(H1N1)pmd09 and A(H3N2) influenza viruses. Vaccine coverage among <18 years recruited SARI cases was very low (3.2%). Seasonal vaccines were moderately effective against type A influenza overall (adjusted VE = 40.5%; 95% confidence interval (CI) = 18.7–56.4%) and subtype A(H1N1)pmd09 viruses (adjusted VE = 55%; 95% CI = 34.5–69.1%), but ineffective against subtype A(H3N2) viruses (adjusted VE = 2.5%; 95% CI = −50.0–36.7%). Both Fluad and Fluarix Tetra vaccines were effective against type A influenza overall and subtype A(H1N1)pdm09 viruses. VE appeared to be similar across age groups (0–64 years, ≥65 years). Seasonal influenza vaccines in the 2018/19 season were moderately effective in preventing SARI caused by A(H1N1)pdm09 influenza but ineffective against A(H3N2).