Age-related responses to influenza vaccination in the Newcastle region during 1983 and 1984

A study was carried out in Newcastle to assess responses to influenza vaccines in elderly nursing home patients and in younger adults during 1983 and 1984. The decision to vaccinate the elderly subjects was made by their general practitioners. A concurrent randomized placebo-controlled trial of the same vaccine was performed in young adult volunteers. Elderly subjects generally possessed higher levels of pre-existing antibody to the influenzal haemagglutinins that were present in the vaccines than did younger subjects. The highest levels were observed in the 52-63 years' age group. Younger subjects showed significantly greater responses to vaccines compared with elderly subjects (P less than 0.05). Peak responses were noted in the 16-24 years' age group. Of a total of 326 elderly subjects (70% of whom had been vaccinated), six participants, two of whom had been vaccinated, contracted laboratory-proven influenza during 1983. Only one unvaccinated subject of a total of 365 subjects (50% of whom had been vaccinated) contracted influenza during 1984. In both years illness was produced by strain A/Philippines/2/82.