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APHA Scientific Session and Event Listing

Itamar Grotto, MD, MPH¹, Ran Balicer, MD, MPH¹, Zehava Smetana, PhD², Nadav Davidovitch, MD, MPH, PhD³, Yael Bar-Zeev⁴, Salman Zarka, MD, MPH⁵, Ella Mendelson, PhD², and Michael Huerta, MD, MPH⁶. (1) Epidemiology Department, Ben-Gurion University of the Negev, PO BOX 653, Beer-Sheva, 84105, Israel, +972-8-6477640, grotto@netvision.net.il, (2) Central Virology Laboratory, Sheba Medical Center, Tel Hashomer, Ramat-Gan, 52621, Israel, (3) Sociomedical Sciences, Mailman School of Public Health, Columbia University, 722 West 168th Street, 9th floor, New York, NY 10032, (4) Army Health Branch, Medical Corps, IDF, 02149, Tel Hashomer, Israel, (5) Army Health Branch and Haifa University School of Public Health, Medical Corps, IDF and Haifa University, 02149, Tel Hashomer, Israel, (6) Ben Gurion University - Barzilai Medical Center Campus, Ashkelon District Health Office, Ashkelon, 78306, Israel

Background: The epidemiology of chickenpox in Israel is changing due to the overall increase in standard of living and the increasing – but not universal – uptake of live attenuated varicella vaccine. Determining the level of susceptibility to varicella is of marked importance in interpreting disease incidence trends and in designing and evaluating public health preventive strategies. We aimed to evaluate the level of susceptibility to varicella among young adults, and compare them with previous data on a similar population. Methods: We conducted a population-based seroprevalence study of IgG antibodies against varicella zoster virus among 540 young adults recruited to mandatory military service in Israel at age 18 years in 2003. Overall and specific rates based on sex, origin, and level of education were calculated. We also compared these results to a previous study in a similar population. Results: The overall 2003 seroprevalence rate was 91.1% (95%CI 88.5-93.3%). The rate was lower among subjects with fewer then 12 years of schooling (85.2%, p=0.015). No statistically significant differences were observed when data were stratified by gender or origin. The 2003 seroprevalence rate was significantly lower than that observed in a similar population in 1992 (98.4%, p<0.001). Conclusions: The level of immunity among young adults in Israel is still high but declining, potentially below herd immunity thresholds. These results must be considered when determining pre- and post-exposure vaccination policy among young adults in crowded settings. Varicella vaccine should be considered to control chickenpox outbreaks, which can now be expected in these conditions.

Learning Objectives: At the conclusion of the session, the participant in this session will be able to

• Recognize the possible impact of different varicella vaccination strategies on the suscptibility of the population at different age groups
• Analyze time trends of seroprevalence of vaccine preventable diseases in order to study the time and place specific epidemiology of the disease
• Apply the results in order to develop pre- and post-exposure varicella vaccination policy among young adults

Keywords: Infectious Diseases, Prevention

Presenting author's disclosure statement:

Not Answered