Trend study on HBsAg prevalence in Thai voluntary blood donors.

: In 1973, the prevalence of HBsAg positive individuals was 9.33% in new army recruit blood donors and 8.28% in the general population (CIEP). The hepatitis B vaccine, which was introduced to use in Thailand in 1985, seems to be effective in reducing the prevalence of hepatitis B carriers year after year. In 1991, the prevalence of HBsAg in new blood donors (74,530) was 6.45% (RPHA). However, it was still relatively high at 8.38% in new army recruit blood donors, while in the general population it had decreased to 6.75%. The data suggested that carriers were more likely to be found in new army recruit blood donors, because most of them are from lower socioeconomic groups, less well educated, from rural areas and sexually active. Therefore, the immunization against hepatitis B must be considered for this high risk group in order to reduce the number of hepatitis B carriers.