RESUMO
AIM: To evaluate the protective effect of inactivated hepatitis A vaccine (Healive) against hepatitis A outbreak in an emergency vaccination campaign. METHODS: During an outbreak of hepatitis A in Honghe Town, Xiuzhou District, Jiaxing City, Zhejiang Province, two nonrandomized controlled trials were conducted in September 2006. The first trial was to vaccinate 108 anti-HAV negative individuals with close contacts of the patients from September with 1 dose of an inactivated hepatitis A vaccine, Healive. The control group comprised of 115 individuals with close contacts of the patients before September. The second trial was to vaccinate 3365 primary and secondary school students who volunteered to receive a dose of Healive and 2572 students who did not receive Healive serving as its controls. An epidemiological survey was conducted to evaluate the protective efficacy of the vaccine. RESULTS: A total of 136 hepatitis A cases were reported during an outbreak that started in June, peaked in August and September, and ended after December of 2006. After a massive vaccination of school children in September, the number of cases declined significantly. No hepatitis A was detected in the 108 vaccinated individuals with close contacts of patients, whereas 4 cases of hepatitis A were found in the controls. The infection rate of hepatitis A was not significantly different in the individuals with close contacts of patients whether or not they received the vaccine (P = 0.122). No hepatitis A was detected in the 3365 students who received the vaccine, four cases of hepatitis A were found in the controls. The infection rate of students with or without vaccination was significantly different in the students who received the vaccine (0/3365 vs 4/2572, P = 0.035). The protective efficacy of the vaccine was 100%. CONCLUSION: Inactivated hepatitis A vaccine demonstrates a good protective effect against an outbreak of hepatitis A.