Adjuvanted versus nonadjuvanted influenza vaccines and risk of hospitalizations for pneumonia and cerebro/cardiovascular events in the elderly

ABSTRACT

Background: The higher effectiveness of MF59®-adjuvanted trivalent influenza vaccine (MF59-TIV) vs. nonadjuvanted TIV in preventing influenza-related hospitalizations was found considering few influenza seasons, local and heterogeneous settings. This study evaluated the relative vaccine effectiveness (rVE) of MF59-TIV vs. nonadjuvanted TIV on the risk of hospitalization for pneumonia and cerebro/cardiovascular events across 15 consecutive influenza seasons.

Research design and methods: Using Health Search Database, a case–control study was nested in a cohort of elderly vaccinated with MF59-TIV or TIV. Conditional logistic regression was used to estimate the odds ratio with 95% confidence intervals (CI) of hospitalizations potentially related to influenza in patients vaccinated with MF59-TIV or TIV.

Results: Of 43,000 patients vaccinated with MF59-TIV (66.2%) and TIV (33.8%) for the first time, 103 cases of hospitalization for pneumonia or cerebro/cardiovascular events (0.11 per 1,000 person-weeks) during 15 influenza seasons were identified. The MF59-TIV was associated with a reduced risk of hospitalizations for pneumonia and cerebro/cardiovascular events vs. TIV [rVE: 39% (95% CI: 4–61%)].

Conclusions: In a 15-season cohort of elderly, MF59-TIV seems to reduce the risk of hospitalizations for pneumonia and cerebro/cardiovascular events when compared with nonadjuvanted TIV. Our findings support the recommendation for MF59-TIV in the elderly population.

KEYWORDS:

• Influenza vaccines
• hospitalization
• pneumonia
• stroke
• myocardial infarction
• primary care

Data availability statement

Not applicable.

Article highlights

• This study evaluated the relative vaccine effectiveness of MF59®-adjuvanted trivalent influenza vaccine (MF59-TIV) as compared to nonadjuvanted TIV on the risk of hospitalization for pneumonia and cerebro/cardiovascular events in a cohort of patients aged ≥65 years.

• Of 43,000 elderly, incidence rate of hospitalizations for pneumonia and cerebro/cardiovascular events was 0.11 (95% CI: 0.09–0.13) per 1,000 person-weeks.

• In a 15-influenza-season cohort of Italian elderly, MF59-TIV was associated with a 39% reduced risk of hospitalizations for pneumonia and cerebro/cardiovascular events as compared to TIV.

Ethical statement

This is an observational, retrospective, non-interventional study. According to a by-law on the classification and implementation of observational drug-related research, as issued by the Italian National Drug Agency (an entity belonging to the Italian Ministry of Health), the present study does not require approval by an Ethics Committee in Italy (Italian Drug Agency note of 3 August 2007).

Declaration of interest

F Lapi and E Marconi provided consultancies in protocol preparation for epidemiological studies and data analyses for, Novartis GSK, MSD, and Seqirus. V Baldo received grants from GSK, MSD, Pfizer, Sanofi, and Seqirus for taking part in advisory boards, expert meetings, being a speaker or an organizer of congresses/conferences, and acting as promoter of epidemiological studies partially supported by vaccine producers. C Cricelli, A Sessa, and A Rossi provided clinical consultancies for Novartis GSK, MSD, and Seqirus. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Authors contributions

F Lapi, A Rossi, and C Cricelli were involved in the study conception and design. M Simonetti and F Lapi were involved in the analysis of the data. F Lapi, E Marconi, V Baldo, A Rossi, A Sessa, and C Cricelli were involved in interpretation of the data, drafting the paper and in revising it critically for intellectual content. All authors approved the final version to be published. All authors agree to be accountable for all aspects of the work.

Geolocation information

Health Search, Italian College of General Practitioners and Primary Care

Via del Sansovino 179, 50142, Florence, Italy.

Supplementary material

The supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the Seqirus SRL, which had no role in any aspect of study design, data analysis and interpretation of the results.