Rapid Decline of Influenza Vaccine–Induced Antibody in the Elderly: Is It Real, or Is It Relevant?

Abstract

Advisory committees have cautioned that influenza vaccine-induced antibody declines more rapidly in the elderly, falling below seroprotective levels within 4 months. We conducted a literature review to assess this assertion. The articles that were included in this review reported antibody levels > or =4 months after influenza immunization in persons > or =60 years old, interpretable in the context of annual influenza vaccine-approval criteria (seroprotection/seroconversion) specified by the Committee for Proprietary Medicinal Products (CPMP) for the elderly. The final review included 14 studies; 8 of which reported seroprotection rates. Seroprotection exceeding CPMP criteria was maintained > or =4 months after influenza immunization in all 8 of the studies reporting this for the H3N2 component and in 5 of the 7 studies reporting this for the H1N1 and B components. In determining whether CPMP criteria were met at season's end, primary antibody response appeared to be more relevant than secondary antibody decline. Both studies reporting seroprotection rates that failed CPMP criteria > or =4 months after influenza immunization for each of the H1N1 and B components had also reported failed seroprotection at 1 month after immunization. If initially achieved after immunization, seroprotection rates of 70%-100% were maintained not just at 4 months (2 studies) but also at 5 months (2 studies) and even at >6 months (4 studies), for the H3N2 and H1N1 vaccine components. Seroprotection rates appeared less consistent for the B vaccine component, throughout the postimmunization period. Seroconversion appears to vary substantially and inversely with preimmunization titers but not with age. In 2 of 6 studies reporting seroconversion alone, CPMP criteria were still met at 4 months. In the other 4 studies, the main reason for failure at 4 months was primary failure at 1 month. A total of 6 studies compared antibody persistence by age, and no consistent differences were found on that basis. The historic concern that the influenza vaccine-induced antibody response in the elderly declines more rapidly and below seroprotective levels within 4 months of immunization should be reconsidered.

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

“…5 Few other studies of ADV have included extended follow-up serology but Ruf et al 38 also reported no advantage in seroprotection rates for ADV over TIV, 4 and 8 mo after vaccination of German seniors. The tendency for protective titers to persist for 6 mo and longer after TIV in elderly adults was highlighted in a recent literature review 39 and is important for season-long protection against influenza infection.…”

Persistence of influenza vaccine-induced antibody in lung transplant patients and healthy individuals beyond the season

“…This variation is not a new observation and is supported by other studies. 11 The fact that we measured antibody persistence beyond one season is unique to our study. Our findings indicate that antibody to influenza B virus is least persistent after vaccination waning from 100% after the first year to between 50-16% the second year.…”

Vaccine effectiveness in older individuals: What has been learned from the influenza-vaccine experience

“…anti-HA antibody responses induced in previously unvaccinated persons) had been noted in older adult populations compared to younger adults in two reviews (Goodwin et al, 2006;Beyer et al, 1989). However, both approaches highlight serious methodological flaws which include a failure to exclude participants with (i) conditions that have influence on the immune system; (ii) those previously vaccinated and (iii) those with high pre-vaccination titers (Skowronski et al, 2008) (see below).…”

“…Although the early decrease in protective anti-HA antibody levels (within 4 months following vaccination) is frequently raised as a concern with respect to the timing of vaccination of elderly individuals (Smith et al, 2006), a recent review conducted by Skowronski et al (2008) suggests this may not be an issue. Amongst the 14 studies included in this review, 8 reported seroprotection rates (Ruf et al, 2004;MacKenzie, 1977;Peters et al, 1988;Delafuente et al, 1998;Buxton et al, 2001;Brydak et al, 2003;Praditsuwan et al, 2005;Hui et al, 2006) and 6 seroconversion rates alone (McElhaney et al, 1993;Powers et al, 1995;Van Hoecke et al, 1996;Minutello et al, 1999;Mysliwska et al, 2004;Keylock et al, 2007).…”