As compared with an intramuscular injection of full-dose influenza vaccine, an intradermal injection of a reduced dose resulted in similarly vigorous antibody responses among persons 18 to 60 years of age but not among those over the age of 60 years.

The RTS,S/SBAS2 vaccine confers sterile protection against Plasmodium falciparum sporozoite challenge. The mechanisms underlying this are of great interest, yet little is known about the immune effector mechanisms induced by this vaccine. The immune responses induced by RTS,S/SBAS2 were characterized in 10 malaria-naive volunteers. Several epitopes in the circumsporozoite protein (CSP) were identified as targets of cultured interferon (IFN)-gamma-secreting CD4+ T cells. RTS,S-specific IFN-gamma-secreting effector T cells were induced in 8 subjects; this ex vivo response mapped to a single peptide in Th2R. CSP-specific CD8+ cytotoxic T lymphocytes were not detected. RTS, S-specific IFN-gamma production was universal, whereas interleukin-4 and -5 production was rare. RTS,S-specific lymphoproliferative responses and antibodies to CSP were strongly induced in all volunteers. Responses waned with time but were boostable. Thus, RTS, S/SBAS2 is a potent inducer of Th1-type cellular and humoral immunity. These results highlight possible immune mechanisms of protection and have important implications for vaccine design in general.

No abstract

We have compared the immunogenicity profile of a recombinant lipoprotein outer-surface protein A (OspA) Lyme disease vaccine administered on schedules of 0, 1, and 6 months (group 1) or 0, 1, and 12 months (group 2) to 800 healthy subjects, aged 15-50 years. One month after the second dosing, geometric mean titers of IgG antibodies to OspA were 1,309 ELISA units (EL.U)/mL in group 1 and 1,404 EL.U/mL in group 2. One month after the third dosing, the titers were 7,205 EL.U/mL and 10,659 EL.U/mL, respectively. Using bioequivalence methodology, we showed that the two vaccination schedules elicit an equivalent immune response 1 month after administration of dose 3: at that point, 91%-93% of all subjects had titers > or =1,400 EL.U/mL, proposed to be protective for one tick season. The vast majority of local and systemic symptoms were mild to moderate and of limited duration. The 0, 1, and 6 months vaccination schedule is a viable alternative to the 0, 1, and 12 months schedule and can provide protection against Lyme disease during one tick season.

The immunogenicity of influenza vaccination in elderly institutionalized patients, with a variety of clinical disorders, was tested in an open multicenter study involving 495 people (mean age 80 years). Vaccination with an inactivated split influenza vaccine (Fluarix^TM) was clinically well tolerated. For all age ranges and all strains of virus, the vaccine elicited a humoral response which surpassed the European Community requirements for influenza vaccines in adults over 60 years. The geometric mean titers for all vaccine strains were significantly increased 28 days after vaccination, and remained higher than prevaccination levels after 6 months. These immunological parameters were unaffected by the clinical status of the patients.