Hepatitis B virus (HBV) infection is a severe public health problem in China. The national serosurvey in 1992 revealed that the prevalence of hepatitis B surface antigen (HBsAg) was 9.8% in whole population, and the prevalence of hepatitis B was especially serious in the western areas. Gansu province, in the north-west, has low socioeconomic conditions, and its medical and sanitary status is lagging. The 1992 serosurvey indicated the prevalence of HBsAg and anti-HBc in Gansu was as high as 7.3% and 45.7% respectively, but the prevalence of anti-HBs was only 34.0%.1
In 2006, the Chinese government conducted the serosurvey across the whole country and 2,200 residents in five national disease surveillance points (DPS) in Gansu were surveyed by multi-stage sampling. The detailed methods were reported elsewhere2.
Compared with the 1992 serosurvey, this serosurvey shows the obvious decline of HBV prevalence in Gansu.
Of the 2,200 surveyed, 3.9% were positive for HBsAg, 45.8% positive for anti-HBs and 20.4% positive for anti-HBc. Compared with the 1992 serosurvey, the present serosurvey shows obvious differences in HBV serological markers. The HBsAg prevalence in this serosurvey significantly decreased by 45.9%; anti-HBc declined by 55.4%; anti-HBs increased by 35.0% (p<0.001 for all comparisons) (Figure 1).
The relationship between the status of hepatitis B immunisation and HBV serological markers indicates the important role of hepatitis B immunisation.
In this serosurvey, 48.2% were immunised against hepatitis B, 43.0% were not vaccinated, and 8.8% had an unknown immunisation history. Different statuses of hepatitis B immunisation have significant differences among the distributions of HBV prevalence. The HBsAg prevalence among vaccinated persons is only 1.9%, compared to 5.4% among unvaccinated persons and 4.2% among persons with unknown immunisation history (p<0.001). The prevalence of anti-HBs among vaccinated persons is significantly higher than that among unvaccinated people (64.5% vs. 34.0%, p<0.001). Contrarily, vaccinated persons have obviously lower anti-HBc prevalence (p<0.001) (Table 1).
|Status of HB immunisation||Number Tested||HBsAga||Anti-HBsa||Anti-HBca|
|Prevalence%||95% CI||Prevalence%||95% CI||Prevalence%||95% CI|
The logistic regression analysis on influence factors of HBV prevalence shows the protective effect of Hepatitis B immunisation against HBV.
The multivariable non-conditional logistic regression was carried out to identify the significant factors associated with HBV infection. The dependent variable was the HBsAg prevalence. The independent variables included gender, occupation, age, blood transfusion, blood donation, Hepatitis B immunisation and so on. The results indicated that blood transfusion was the risk factor (OR =4.0, p=0.035), and hepatitis B immunisation was the protective factor (OR =0.5, p=0.032) (Table 2).
|Variable||ß value||S.E.||Wald||p value||OR||95% CI|
|Hepatitis B immunisation||-0.7||0.3||4.6||0.032||0.5||0.3- 0.9|
The serosurvey results showed that Gansu has made great progress in controlling hepatitis B. In the whole population, the HBsAg prevalence decreased to 3.9%, which achieved the national goal of less than 7% by 2010, and the anti-HBs and anti-HBc prevalences also had significant changes. The decline of HBV prevalence is due to the hepatitis B immunisation. The present finding indicates that broad immunisation has a great impact on the prevalence of Hepatitis B in whole population. Compared with unvaccinated persons, vaccinated persons have lower HBsAg and anti-HBc prevalences. Additionally, the logistic regression analysis highlights the significant factor – hepatitis B immunization, which supplies effective protection against hepatitis B in population. These data are consistent with many studies in other countries.3,4 For example, after the introduction of universal Hepatitis B vaccination for infants and adolescents in Victoria, Australia, the HBsAg prevalence in those groups was lower than established estimates.3
To control and eliminate HBV infection worldwide has been proposed as an achievable public health strategy. Our work indicates that controlling HB can be achieved with a comprehensive immunisation strategy, including free immunisation for infants, catch-up vaccination programs for adolescents and expanded vaccination for adults. In other undeveloped areas or countries with high HB prevalence, a similar strategy is worth consideration.