Ricerc@Sapienza

Between September 2017 and February 2018, influenza A(H1N1)pdm09, A(H3N2) and B viruses (mainly B/Yamagata, not included in 2017/18 trivalent vaccines) co-circulated in Europe. Interim results from five European studies indicate that, in all age groups, 2017/18 influenza vaccine effectiveness was 25 to 52% against any influenza, 55 to 68% against influenza A(H1N1)pdm09, -42 to 7% against influenza A(H3N2) and 36 to 54% against influenza B. 2017/18 influenza vaccine should be promoted where influenza still circulates.

Background: Evidence on influenza vaccine effectiveness (VE) in preventing mortality and morbidity in the elderly is weak. Our aim was to measure the VE against severe outcomes in the elderly. Methods: We conducted a multicentre hospital-based test-negative design (TND) case-control study, during the 2017/18 season, in four Italian hospitals. The study population included individuals aged ?65 years hospitalized with Severe Acute Respiratory Infections (SARI). Patients were classified as cases and controls based on the results of the PCR influenza testing.

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.