Numerous studies have explored whether the antibody response to influenza vaccination in elderly adults is as strong as it is in young adults. Results vary, but tend to indicate lower post-vaccination titers (antibody levels) in the elderly, supporting the concept of immunosenescence – the weakening of the immunological response related to age. Because the elderly in such studies typically have been vaccinated against influenza before enrollment, a confounding of effects occurs between age, and previous exposures, as a potential extrinsic reason for immunosenescence. We conducted a four-year study of serial annual immunizations with inactivated trivalent influenza vaccines in 136 young adults (16 to 39 years) and 122 elderly adults (62 to 92 years). Compared to data sets of previously published studies, which were designed to investigate the effect of age, this detailed longitudinal study with multiple vaccinations allowed us to also study the effect of prior vaccination history on the response to a vaccine. In response to the first vaccination, young adults produced higher post-vaccination titers, accounting for pre-vaccination titers, than elderly adults. However, upon subsequent vaccinations the difference in response to vaccination between the young and elderly age groups declined rapidly. Although age is an important factor when modeling the outcome of the first vaccination, this term lost its relevance with successive vaccinations. In fact, when we examined the data with the assumption that the elderly group had received (on average) as few as two vaccinations prior to our study, the difference due to age disappeared. Our analyses therefore show that the initial difference between the two age groups in their response to vaccination may not be uniquely explained by immunosenescence due to ageing of the immune system, but could equally be the result of the different pre-study vaccination and infection histories in the elderly.

HighlightsAlthough it is not known which one of two influenza B lineages will circulate in any one season, only a representative virus of one of the two lineages is part of the trivalent seasonal influenza vaccine.We describe three lineage selection strategies to choose which lineage to include in the seasonal vaccine, including the common strategy of using the last lineage that has been observed to dominate, and a new strategy which takes into account population immunity.We show why the “hedging strategy” leads to higher expected vaccine efficacy for influenza B by describing the underlying immunity management mechanism.We show that the hedging strategy would have lead to higher vaccine efficacy to influenza B in the seasonal vaccine in the decade 2000–2010.We show that some of the benefit of transferring to a quadrivalent vaccine can be captured without the cost of moving to a quadrivalent vaccine with an improved trivalent vaccine lineage selection approach.

The tendency for public welfare spending to be increasingly aimed at the elderly has been identified in several developed countries. While population aging is a common trend, it is not obvious why the shift in spending exceeds the trend in aging, or why per capita spending on the elderly is increasing. In the first part of the present article, we show that this trend is occurring in Spain, identify the losers from this development, discuss the policies that underlie it, and propose adjustments based on Musgrave's fixed proportions rule for fair intergenerational distribution. These policies aim to manage population aging, labor market participation of youth and women, as well as public policies that combine 'work-fare' strategies with the more traditional 'welfare' strategies. In the second part of this paper, we explore the contribution of public health expenditure to overall public social expenditure, and analyze the effect of increasing health on distributional fairness. This analysis is guided by our perception that social policy, including health policy, should be more horizontal, i.e. it should take into account the sum total of a mixed basket of resources aimed at any recipient group, to avoid the skewed allocation of resources that arises from compounding various independent distributions of resources. Coordination of the various channels of social expenditure should ensure precisely targeted recipients and cross-departmental sources. The normative fairness criterion to be used should be precisely specified. In Spain (1980-2000) the oldest segment of the population has gained the most, appropriating an increased share of resources. This increase goes beyond the amount that could be explained by population aging throughout the period. The 'losers' are individuals with different fragility conditions. On average the youngest working group has suffered the highest relative loss.