Influenza Revaccination of Elderly Travelers: Antibody Response to Single Influenza Vaccination and Revaccination at 12 Weeks

Abstract

The antibody response to a single influenza vaccination and the effect of influenza revaccination was assessed in healthy elderly persons. Travelers > or =65 years old who had received influenza vaccine before travel were enrolled in the study and were offered a second vaccination after 12 weeks. Geographic and age-matched control subjects received a single vaccination. A second influenza vaccination was not associated with increased adverse effects. There was no significant difference between log(10) hemagglutinin-inhibiting (HI) antibody titers or an HI antibody titer > or =1:40 (considered to be protective) in 28 control subjects and 28 revaccinated travelers for any antigen. Probable protection for influenza A antigens remained high 24 weeks after a single immunization and revaccination (A/Sydney/05/97 [H3N2], 92% and 96%, and A/Beijing/262/95 [H1N1], 80% and 96%, respectively). Response to B/Harbin was less throughout the study. A/Sydney antibody titer was lower with more times vaccinated in the previous 5 years. Therefore, a second vaccine did not enhance the immune response.

Guidelines for the management of adult lower respiratory tract infections

“…Annually repeated vaccinations do not lead to a decreasing immune response or protection [294]. Although much less studied, repeated vaccinations annually, or even more frequent, do not lead to more side-effects than after primary vaccination [294,295].…”

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

“…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). Seroprotection rates according to CPMP criteria (Table 1) were maintained ≥4 months after influenza immunization in all 8 for A/H3N2 com-ponent and in 5 of 7 studies for the A/H1N1 and B components.…”

“…Seroprotection rates according to CPMP criteria (Table 1) were maintained ≥4 months after influenza immunization in all 8 for A/H3N2 com-ponent and in 5 of 7 studies for the A/H1N1 and B components. In determining whether serological CPMP criteria were met at season's end, seroprotection rates of 70-100% were maintained not just at 4 months (Delafuente et al, 1998;Buxton et al, 2001) but also at 5 months (Peters et al, 1988;Brydak et al, 2003) and, even at >6 months (Ruf et al, 2004;MacKenzie, 1977;Praditsuwan et al, 2005;Hui et al, 2006) for the A/H3N2 and A/H1N1 vaccine components. In 2 of 6 studies reporting seroconversion alone, criteria were still met at 4 months (Van Hoecke et al, 1996;Mysliwska et al, 2004).…”

Recent advances and new challenges in travel medicine

“…Researchers found that at 24 weeks after vaccination antibody levels remained high in both travelers and controls. The study found no indication of benefit but looked only at antibody response and not protective efficacy [55].…”