Immunization of Elderly People with High Doses of Influenza Vaccine

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Abstract
Healthy ambulatory elderly were immunized with increasing doses of the 1984-1985 influenza vaccine formulation. Two types of vaccines, split-product vaccine (SPV) and whole virus vaccine (WVV), were used. Three different doses, 0.5 mL (the standard volume, 1X), or 1.0 mL (2X), and 1.5 mL (3X) of each of the two vaccines were compared. The size of each of the six groups was between 23 and 26 subjects. The mean ages in each of the groups ranged from 71 to 74 years. No difference in local or systemic reaction was noted among the six groups. A dose-response effect was observed for the SPV recipients to the influenza A/Chile/83 (H1N1) strain. The geometric mean hemagglutination inhibition (HI)titer (GMT) was 1:76 after the 3X dose vs 1:38 after the 1X dose(P < 0.025). To the influenza A/Philippines/82 (H3N2) strain the GMT was 1:70 after the 3X dose vs 1:43 after the 1X dose. A similar trend was noted for the influenza B/USSR/83 strain. A (H1) titer of .gtoreq. 1:40 for all the strains was seen in > 70% of the split product vaccine recipients only after the 3X dose. For the WVV recipients, increasing doses did not result in increasing GMT for any of the three vaccine strains. In addition, HI titers .gtoreq. 1:40 were not uniformly seen in > 70% of the vaccine recipients at any of the three whole virus vaccine doses. In conclusion, a dose three times the standard dose of commercially available inactivated influenza vaccine is not uniformly superior to the standard dose of vaccine. The humoral immune response to influenza vaccine appears to be comparable in healthy elderly adults and in younger adults when most have been previously immunized.