Efficacy of Hepatitis B Vaccination in Personnels of BMA Medical College and Vajira Hospital

Abstract

Efficacy of Hepatitis B Vaccination in Personnels of BMA Medical College and Vajira Hospital

Rattana Boonsirichan MD*

Dussadee Duangmanee RN**

Phensiri Klaewkasikij RN**

Rapeepan Chantanalage RN**

Salisa Suebklay RN**

Busaba Supawattanabodee RN, MSc (biostatistics)***

* Department of Medicine, BMA Medical College and Vajira Hospital

** Infection Control Unit, BMA Medical College and Vajira Hospital

*** Clinical Epidemiology Unit, BMA Medical College and Vajira Hospital

Objectives: To assess the efficacy of hepatitis B vaccine, the waning immunity together with anamnestic response, and factors associated with the immune response.

Study design: Descriptive prospective study.

Subjects: A total of 253 personnels of BMA Medical College and Vajira Hospital, who had received standard 3 doses of hepatitis B vaccine during 2007-2008.

Methods: The subjects were tested for hepatitis B surface antibody (antiHBs) 2 months after complete 3 doses of vaccination. Those who had antiHBs < 10 miu/ml were vaccinated with another dose of vaccine. Only the responders (develop antiHBs > 10miu/ml after 3 or 4 doses of vaccine) were tested for antiHBs in the next 12 months to assess the incidence of waning immunity (antiHBs decline to level < 10 miu/ml). The subjects who had waning immunity were vaccinated with another dose and then were retested for antiHBs about 1 month after revaccinated to assess the rate of anamnestic response (HBsAb > 10 miu/ml after 1 vaccinated dose).

Main outcome measures: responders, waning immunity, anamnestic response

Results: The rate of responder was 98.8% and 99.6% after 3 and 4 doses of vaccination, respectively. All responders who needed 4 doses of vaccine were obese (body mass index: BMI > 25 kg/m²). Only one subject, who was not response to the vaccination, had morbid obesity (BMI 37.3 kg/m²). Waning immunity was found in 6.2% of the responders. Obesity was the only independent factor associated with waning immunity. All who had waning immunity had anamnestic response.

Conclusion: Almost all of the personnels, who received complete course of Hepatitis B vaccine developed adequate protective antibody level. All who had waning immunity had anamnestic response. Hence, periodic antibody testing was not required except in the obese, who may need more doses of vaccine.

Key words: hepatitis B vaccine, responder, waning immunity, anamnestic response

Vajira Med J 2009 ; 54 : 9 - 18