[An investigation on immunological effect of hepatitis B vaccine amongst adult population in high-labor-export rural regions, under 4 different strategies]

Objective: To grope for an ideal immune strategy in grown-ups via comparison of immunological effects under 4 different vaccination schemes. Methods: Study population was selected by stratified random cluster sampling. A total of 4 different vaccination proposals, including Strategy A (3 doses, 10 μg, administrated repeatedly into the unilateral deltoid muscle at 0-1-6 months), Strategy B (2 doses, 20 μg, administrated into the bilateral deltoid muscles simultaneously), Strategy C (3 doses, 10 μg, administrated repeatedly into the unilateral deltoid muscle at 0-1-2 months) and Strategy D (2 doses, 10 μg, administrated to the bilateral deltoid muscles at the same time), were conducted in Liangzhou, Minqin Gulang, and the Tianzhu Tibetan Autonomic county respectively, in Wuwei city, Gansu province. Under 4 different strategies, post-vaccination immunological effectiveness was evaluated when blood samples of participants collected in the eighth months, post-first injection and in the third year, and tested by enzyme-linked immunoassays and electro-chemiluminescence immunoassay. Chi -squared test and Fisher exact test were used to evaluate the immunological differences between the 4 strategies. Wilcoxon’ s signed rank test and Kruskal-Waillis H test were conducted to compare the differences of the geometric mean titers (GMTs) of antibody against HBV surface antigen (anti-HBs) titers. Results: A total of 1 621 eligible participants aged 16 to 60 years old, were recruited for the study. Numbers of administration and gender were testified as the presuming factors for influencing immune effectiveness. The vaccination completion rates were 53.97% and 79.82% in Strategy A and C, respectively, and the difference statistically significant ( P <0.05). In the first year, the protective antibody sero-conversion rates (standardization rate) were 89.21%, 54.88%, 92.11%, and 41.63%, in Strategy A, B, C and D, respectively, and the significant statistically differences emerged ( P <0.05) if Strategy B, C and D were compared with Strategy A (as the gold standard). Over a 3-year follow-up period, the levels of GMTs on protective antibody declined from 179.2 IU/L, 51.6 IU/L, 277.1 IU/L and 10.1 IU/L to 61.3 IU/L, 21.2 IU/L, 31.8 IU/L and 6.0 IU/L in Strategy A, B, C and D, respectively, and the differences of declination on GMTs showed statistically significant differences ( P <0.05) when compared within or between the 4 strategies. Conclusion: The 0-1-2 months’ prophylactic schedules (Strategy C) seemed superior to the others, in terms of effectively inducing the protective antibody, with shorter duration of vaccination, persisting longer immunity and having higher rate of completive vaccination, so is worth to be recommended as a feasible immune programme for adults, especially for migrants from the rural regions.