Effectiveness of Adjuvanted Influenza Vaccination in Elderly Subjects in Northern Italy

Abstract

Although vaccination against influenza is recommended for elderly and high-risk patients in many countries, efficacy in the elderly has been suboptimal. The MF59 adjuvanted trivalent inactivated vaccine (ATIV) was developed to increase the immune response of elderly subjects to influenza vaccination, but its effectiveness has not yet been well documented. This prospective, observational study evaluated the relative effectiveness of ATIV versus nonadjuvanted trivalent inactivated vaccine (TIV) in individuals at least 65 years of age in Lombardy, northern Italy. Hospitalizations for influenza or pneumonia (International Classification of Diseases, Ninth Revision, Clinical Modification, codes 480–487) during the 2006–2007, 2007–2008, and 2008–2009 influenza seasons were identified from administrative databases. Stratified and regression analyses, including the propensity score to adjust for confounding, as well as generalized estimating equations to account for repeated vaccination, were used. Overall, 107,661 records were evaluated, contributing 170,988 person-seasons of observation. Since ATIV is preferentially recommended for more frail individuals, subjects vaccinated with ATIV were older and had more functional impairment and comorbidities. In the primary analysis, risk of hospitalization for influenza or pneumonia was 25% lower for ATIV relative to TIV (relative risk = 0.75, 95% confidence interval: 0.57, 0.98). To the extent that there is residual bias, ATIV is likely to be even more protective than this result suggests.

Safety, immunogenicity, and tolerability of three influenza vaccines in older adults

“…A modeling exercise using Canadian data for influenza infections projected that even small increases in vaccine effectiveness with ADV over TIV would be cost-effective. 33 An observational study in elderly adults in Northern Italy 34 reported a lower rate of influenza-like illness or pneumonia after ADV relative to TIV but only after multiple data adjustments, which were open to criticism. 35 A recent comparison of TIV vaccines 36 with and without AS03 adjuvant (also squalene-based, like ADV) in elderly people indicated modestly greater relative efficacy (17%) of the adjuvanted vaccine vs. laboratory confirmed influenza A in one of two seasons studied.…”

Cross-protection against drifted influenza viruses

“…Recently, Mannino et al, in a prospective, observational, population-based cohort study, throughout 3 vaccination seasons (2006-2007, 2007-2008 and 2008-2009), demonstrated that vaccination with MF59™-adjuvanted trivalent inactivated vaccine reduced the risk of hospitalization for influenza or pneumonia (without positive laboratory confirmation of influenza virus) in the elderly, during the peak of influenza season by 25% relative to vaccination with plain trivalent inactivated vaccine. 71 The epidemiological picture observed during the study period was characterized by both good and partial mismatch, although Mannino et al did not evaluate the effectiveness according to the pattern of circulating viruses.…”

Impfstoffkonzepte in der Pandemieplanung – Wichtige Aspekte aus dem Nationalen Pandemieplan Teil II

“…Eine eindeutige Überlegenheit adju vantierter gegenüber nichtadjuvantier ter saisonaler Impfstoffe erscheint jedoch zum jetzigen Zeitpunkt, auch durch zu sätzlich verfügbare Beobachtungsstudien [38,39], nicht gesichert. [40,41].…”