Preexisting immunity to diverse respiratory adenovirus serotypes among young adults in the United States, 1998-2008

Session I: Metzgar, D.

Title of Contribution: Preexisting immunity to diverse respiratory adenovirus serotypes among young adults in the United States, 1998-2008

Author(s): David Metzgar1, Angelia Eick2, Ryan Ortiguerra1, Adriana Kajon3, Dean Erdman4, Kevin Russell1,5, Dennis Faix1, Patrick Blair1

Affiliation(s): 1Department of Respiratory Disease Research, Naval Health Research Center, San Diego, CA. 2Epidemiology and Analysis, Armed Forces Health Surveillance Center, Silver Spring, MD, 3Infectious Disease Program, Lovelace Respiratory Research Institute, Albuquerque, NM. 4Centers for Disease Control and Prevention, Respiratory and Enteric Viruses Branch, Atlanta, GA. 5DoD Global Emerging Infections Surveillance and Response System, Armed Forces Health Surveillance Center, Silver Spring, MD.

Abstract: Historically, military recruits have suffered essentially continuous epidemics of febrile respiratory illness (FRI) caused by adenoviruses (Ads). The only exception has been the period from 1971 through 1996, during which vaccines against two common adult respiratory Ads (Ad4 and Ad7) were successfully used to control adenoviral FRI. Prior to use of these vaccines, recruit FRI was associated with several serotypes of Ad, including Ad3, Ad4, Ad7, and Ad21. From 1998, when vaccine stocks ran out, through 2005, Ad4 completely dominated the recruit environment, accounting for 95% of adenoviral FRI. In 2007, diversity suddenly increased, with Ad3, Ad21, and Ad14 becoming dominant for long periods of time at specific training sites, while Ad4 continued to dominate at other sites. At the same time, Ad14 swept through civilian communities, causing widespread morbidity and several fatalities. This study was designed to address the role that preexisting immunity (seroprevalence) among host populations might play in driving these abrupt changes in serological diversity and dominance. Serum samples collected before recruits arrived at training sites were used to determine background seroprevalence rates for Ad3, Ad4, Ad7, Ad11, Ad14, and Ad21 among young US adults over the last 10 years. The sample set was split by sex, birth year cohort, recruit training year cohort, and recruit training site. The results show that immunity to species B1 adenoviruses, including Ad3 and Ad7, has generally been high over the last 10 years, while immunity to Ad4 (species E) has been relatively low, and immunity to Ad14 (species B2) was essentially nonexistent. These relationships suggest that host factors and herd immunity may play a very important role in the pattern of adenoviral distribution and association with disease in specific age groups and at-risk populations.