Summer 1996 Volume 1, Number 2		Hepatitis B control: success stories The big story from Rome was the tremendous success of hepatitis B control programs around the world. These programs have measurably reduced HBV infection, cut the prevalence of the hepatitis B carrier state, and, in a couple of early studies, decreased the incidence of hepatocellular carcinoma (HCC), the most serious sequela of chronic hepatitis B infection. Dr. D.S. Chen, from the Hepatitis Research Center in Taipei, Taiwan, fascinated conferees with his description of the Taiwanese hepatitis B control program. The program was launched in July 1984; universal vaccination of infants began in 1986. Prior to the program, Taiwan had a high hepatitis B carrier rate - about 7-10%. Dr. Chen and his colleagues recently evaluated their program using several methods. In one, they conducted random blood drawings of 3,000-4,000 children. In the 6-year-old cohort, the hepatitis B surface antigen (HBsAg) prevalence rate decreased from 10% for those born in 1983, to 0.7% for those born in 1987. In a second study done near Taipei city, researchers conducted follow-up serologic studies 5 and 10 years after the vaccination began. HBsAg prevalence decreased from 9.8% before the vaccination program began, to 4.8% in 1989, to 1.3% in 1994. Dr. Chen said it would take 50 years to see the full impact of the program on HCC rates, because the average age of Taiwanese HBsAg seropositive HCC patients is 55-60 years. But, he said, it is not too early to measure the program's effect on the HCC rate in young children. The annual incidence of hepatocellular carcinoma in Taiwanese children ages 6-14 has fallen from 4.5-7.1 per 100,000 children in 1981-91, to 1.7 per 100,000 in 1992 and 2.4 per 100,000 in 1993. Dr. Chen closed his talk by telling the entranced audience, only half jokingly, that the success of the Taiwan program means that "in the year 2040 or so, Taiwan oncologists will lose their jobs." Mainland China has long been recognized as an area of hyperendemic hepatitis B infection. Dr. Z.Y. Xu, of Shanghai Medical University, described the extraordinary progress in control of hepatitis B there. The Chinese program uses its own serum-derived vaccine, which is manufactured in six Chinese plants in huge quantities (75 million doses in 1995). In 1996, two more plants will open to produce recombinant vaccine using Merck technology. The Chinese vaccination program, begun in 1986, uses two alternate strategies: low dose vaccination of all newborns without serologic pre-screening of pregnant women, or high dose vaccination of infants born to HBsAg-seropositive mothers after maternal screening. Coverage rates are 98-100%. In areas using the first strategy, HBsAg carriage rates among children ages 0-9 have decreased from 16.3% to 1-2%. In areas using the second strategy, rates in the same age group have dropped from 8.8% to 0.4-0.5%. Dr. Xu said that "universal infant immunization may reduce the carrier state in the Chinese population to about 1% and lower in just one generation." In a related study of long-term vaccine efficacy, Dr. Xu told the conference that anti-HBs seroprevalence in vaccinees dropped from 96% to 68% in the ninth year after vaccination. But there was no accompanying increase in the HBV carrier rate. Furthermore, a small booster dose of only 2.5 micrograms caused rapid seroconversion in 80.8% of children who had lost antibody, indicating a strong immune memory-based response to exposure. He concluded that boosters are unnecessary so far. Dr. T. A. Ruff summarized the hepatitis B control situation in other Asian countries. HB vaccine is integrated into the WHO Expanded Programme on Immunization (EPI) schedule in all but 2 of 36 Western Pacific WHO countries. Some countries already have evidence of success. In Malaysia and Singapore, for example, HBsAg carrier rates have dropped from about 10% to 1-2% in just 3-5 years. In other countries, such as Cambodia and Indonesia, programs are only partly implemented. In the Americas, tremendous progress has been made in Alaska, where HBV infection was hyperendemic in the pre-vaccine era. A prevention program was started in 1983, which included screening of all Alaskan Natives for HBV seromarkers followed by vaccination of susceptibles, routine vaccination of all newborns, and screening of all HBV carriers with alpha-fetoprotein to detect hepatocellular carcinoma at a potentially treatable stage. Dr. Brian McMahon, from the Arctic Investigations Program, CDC, told the conference that about 52,000 Alaskan Natives have been screened and over 60,000 have been vaccinated. In the highest prevalence area of Alaska, the incidence of acute hepatitis B has fallen from 200 per 100,000 per year to zero. Dr. McMahon told conferees that "we have created a generation of hepatitis B-free individuals." In the Alaska program, none of the 60,000 persons who received HBV vaccine since 1981 has had icteric hepatitis B or become a carrier, although a few recipients have converted from negative to positive anti-HB core antibody. Dr. McMahon interprets this to mean that the protection afforded by HBV vaccine lasts at least ten years. In a poster presentation, F. Hofmann and colleagues from Freiburg, Germany cited success in reducing the prevalence of HBV seromarkers in hospital workers (Changes in HBV-prevalence due to hepatitis B vaccination: Results of three prevalence studies in 1984/85, 1989/90 and 1994/95. F Hofmann, HM Hasselhorn, N Krall, M Michaels, H Berthold). In another poster, RPB Larke and colleagues from Alberta, Canada reviewed their success in screening prenatal women for HBV and delivering vaccine to newborns. In Alberta, of 685 infants born to HBsAg-seropositive mothers, 95.5% have been given HBIG and 3 doses of vaccine. In 1994, the group was unable to find a single HBsAg-seropositive infant born to a carrier mother (A decade of success for Canada's earliest province-wide program to prevent mother-to-infant transmission of HBV infection. RPB Larke, JR Waters, JS Pagnucco).