Abstract
BackgroundThe age-related weakening of the immune system makes elderly subjects less responsive to influenza vaccination. In the last years, two “enhanced vaccines” were licensed for individuals aged ≥65 years, one being a subunit vaccine (Fluad®) containing the MF59 adjuvant administered intramuscularly (IM-MF59) and the other one a split non-adjuvanted vaccine administered intradermally (Intanza® 15mcg) (ID). In the present study, we evaluated and compared the antibody responses against the three vaccine antigens and heterovariant A(H3N2) circulating viruses induced by IM-MF59 and ID influenza vaccines in 80 elderly institutionalized volunteers (40 per group) during the Winter season 2011–2012.ResultsHemagglutination inhibiting (HI) antibody titers were assessed in blood samples collected before, 1 and 6 months after vaccination. One month after vaccination both the IM-MF59 and ID vaccines induced increases in HI titers against all the three vaccine strains. The results in the two groups were similar against the A(H3N2) and A(H1N1) strains. Responses against the B strain typically tended to be higher after ID than IM-MF59, yet both vaccines stimulated lower responses against the B strain than against the two A strains. The two vaccines induced favorable results also against four epidemic drifted A(H3N2) viruses circulating in Winter 2011–2012. Six months after vaccination, the HI titers decreased in both groups.ConclusionThe responses induced by IM-MF59 and ID vaccines in institutionalized elderly people were similar against the A(H3N2) and A(H1N1) strains but frequently higher, for the ID, against the B strain. The two vaccines induced positive responses against drifted A(H3N2) circulating viruses.
Highlights
The age-related weakening of the immune system makes elderly subjects less responsive to influenza vaccination
Forty volunteers were vaccinated with MF59-ajuvanted trivalent intramuscular influenza vaccine (IM-MF59) and 40 with Intradermal trivalent influenza vaccine (ID) influenza vaccine commercially available for the 2011–2012 Winter season
Because of the importance of documenting the ability of the influenza vaccine to induce heterologous immune responses, we examined the induction of Hemagglutination inhibiting (HI) antibody responses against those four drifted A (H3N2) viruses following immunization with the two different enhanced 2011–2012 influenza vaccines
Summary
The age-related weakening of the immune system makes elderly subjects less responsive to influenza vaccination. We evaluated and compared the antibody responses against the three vaccine antigens and heterovariant A(H3N2) circulating viruses induced by IM-MF59 and ID influenza vaccines in 80 elderly institutionalized volunteers (40 per group) during the Winter season 2011–2012. The second vaccine was a split non-adjuvanted vaccine administered intradermally (Intanza®) (ID), supposed to reach the same goal by reliably delivering the vaccine into the immune-rich environment of the dermis [7] In most instances, both vaccines were found to be capable of inducing higher, or comparable, immune responses in the elderly when compared to conventional non-enhanced influenza vaccines [8,9,10,11,12]. The volunteers were institutionalized elderly people and the period of observation was the 2011–2012 Winter season
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
