Secular variations in longevity and in population aging are of huge interest to actuaries. It is shown here that temporal changes in mortality and natality accompany the recycling of influenza A viruses i.e., the re-exposure of human populations, from time to time, to influenza A viruses antigenically similar to viruses (H1, H2, H3) that circulated in the past. Mortality (and natality) change as birth cohorts (whole population and maternal) with specific types and levels of vulnerability to influenza A re-infections, acquired through early-life effects of infection with one (period-specific) influenza A sub-type, course through subsequent influenza A environments over time. Epidemiologic evidence of association between secular trends in mortality (and natality) and interactions between birth-cohort and period effects of influenza A circulation is presented both for the U.K. and the U.S. New interpretations to several epidemiologic and demographic observations follow from this finding.