Serosurveillance of Varicella and Hepatitis B Infection after Reported Cases in Medical Students and the Relationship between Past Varicella Disease History and Immunity Status
Detchvijitr Suwanpakdee MD*, Chalida Laohapand MD*, Visal Moolasart MD*, Prasong Lomtong MD**, Nat Krairojananan MD***, Phutsapong Srisawat MD***, Veerachai Watanaveeradej MD*
Affiliation : * Department of Pediatrics, Phramongkutklao Hospital, Bangkok, Thailand ** Medical department, Phramongkutklao College of Medicine, Bangkok, Thailand *** Student affairs, Phramongkutklao College of Medicine, Bangkok, Thailand
Objective : To identify seroprevalence of varicella and the relationship with their histories of experiences of varicella diseases
and to provide appropriate immunization against varicella, mumps, measles, rubella and hepatitis B to medical students.
Material and Method: All of the medical students were eligible for participation after informed consents. Immunization
history against varicella, mumps, measles, rubella (MMR) and hepatitis B were obtained from a questionnaire. A blood
sample was obtained from each student for IgG antibody against VZV by ELISA. Medical students with an uncertain history
or no documentation of hepatitis B vaccination were tested for HBsAg and anti-HBcIgG by ELISA.
Results : There were 383 medical students enrolled. The mean age at enrollment was 21.6 years (median 21.4 years; range
18-25.8 years). Of 383 medical students, 372 (97.2%) had documents of receiving MMR immunizations. The blood samples
were obtained from 374 of 383 (97.6%) medical students to identify the immunity against varicella zoster virus (VZV) and the
seroprevalence rate was 92%. Using VZV IgG antibody detection as a standard test, history of experience of varicella disease
provided positive predictive value of 99.3% (148/149). Of 383 medical students, 277 (72.3%) were tested for hepatitis B
markers and 243 (87.7%) students showed negative results. The prevalence of HBsAg carriers was 0.01% (4/383).
Conclusion : Suboptimal immunities against vaccine preventable diseases could be demonstrated in the medical students
including varicella and hepatitis B. New recommendations of immunizations against varicella, MMR and hepatitis B viruses
for a particular group of the population were provided.
Keywords : Varicella, Hepatitis B, Measles, Mumps, Rubella, MMR, VZV, HBV, Immunity, Vaccine, Medical student, Seroprevalence, Carriers, Control
