| effect of a hepatitis b vaccination program on the prevalence of hepatitis b virus infection. | in april 1991, surveys for serologic evidence of hepatitis b virus (hbv) infection were conducted among 3- to 4-year-old children born after a hepatitis b immunization program of newborns began and among 6- to 11-year-old children targeted for early childhood vaccination in american samoa. compared with 3- to 4-year-olds tested in 1991, children tested at baseline in 1985 were more likely to have been infected with hbv (5/40 vs. 2/93; prevalence ratio [pr] = 5.8, 95% confidence limits [cl] = 1.2 ... | 1993 | 8418167 |