Follow-up analysis of the incidence of acute respiratory infections among enlisted service members during their first year of military service before and after the 2011 resumption of adenovirus vaccination of basic trainees.

This analysis estimated the incidence rates of acute respiratory infections (ARIs) during the first year of military service for service members in 16 cohorts (designated 1999 through 2014) based on the years in which they began their service. That first year of service was divided into two separate follow-up periods: the first 3 months of service (corresponding to the period of initial entry training) and the next 9 months of service (months 4-12). The surveillance period covered service members whose first years of service were before and after the 2011 resumption of the administration of adenovirus vaccines, types 4 and 7, to enlisted trainees at the beginning of their initial training periods. In general, the findings were that incidence rates of ARIs were relatively high for the cohorts who did not receive the vaccines, and that the rates were dramatically lower in the cohorts (2012-2014) who did receive the vaccines. These observations pertained to both the first 3 months of service and the next 9 months of service. Possible interpretations of these findings and the limitations of the study methods are discussed.