Changes in Clinical Presentation and Epidemiology of Respiratory Pathogens Associated With Acute Respiratory Illness in Military Trainees After Reintroduction of Adenovirus Vaccine

Yun, Heather C.; Young, Adam N.; Caballero, Manuel Y.; Lott, Lisa; Cropper, Thomas L.; Murray, Clinton K.

In 2001, the US Food and Drug Administration's (FDA) newproduct approval process was initiated for resumption of production of Ad4 and Ad7 vaccines by a new manufacturer [14] . Phase 3 vaccine trials demonstrated (1) 99% efficacy for Ad4 and (2) Ad7 (which was not circulating at the time) seroconversion rates of 95% [15] . In 2011, the 2 vaccines were approved by the FDA and reintroduced nearly simultaneously at all 8 US military basic training locations in October/November of that year. Since then, surveillance reports have consistently demonstrated great reductions in FRI and Ad-related illness. Early data indicated a 75% decrease in FRI, and proportions of collected specimens positive for Ad decreased from 75% to 1% in the months surrounding vaccine introduction (VI) [11] . Nearly all of this was attributable to Ad4, with rare detections of serotypes 7, 3, 14, and 21, and 3 cases involving vaccine-type 4p. Follow-up data published in late 2014, evaluating surveillance data from 1996 to 2013, reported reductions in Ad disease burden from 5.9 to 0.02 cases/person-week [16] . The authors estimated that the current vaccines prevent 13 000 cases of FRI, 1100-2700 hospitalizations, and 1 death per year. After VI, Ad14 became the most prevalent circulating serotype, although actual number of cases detected decreased from approximately 610 per year to 44 in 2013. This large study reported comprehensive surveillance data for overall Ad and FRI, but clinical data were not captured. Whether the clinical presentation of those trainees who do present for care with a respiratory illness has changed post-VI is unclear. Because respiratory illness remains a leading cause of presentation for care among military trainees, understanding of trends in clinical presentation and emerging, non-Ad respiratory pathogens in the post-VI era requires evaluation.