We evaluated the immunogenicity and efficacy of hepatitis B vaccine (Heptavax-B) in a randomized, double-blind, placebo-controlled trial involving 1311 patients receiving hemodialysis in the United States. After three doses of vaccine (40 micrograms each) had been administered, 63 per cent of the patients were antibody-positive. After correction for possible passive transfer of antibodies by blood transfusion, only 50 per cent of vaccine recipients were considered vaccine responders. The incidence of hepatitis B viral infection during the 25 months of the trial was much lower than had been anticipated and was virtually the same in the vaccine and placebo recipients (6.4 and 5.4 per cent, respectively). Four cases of hepatitis B occurred in patients who had an apparent antibody response to the vaccine, but in each case either antibody had reached low or undetectable levels before hepatitis B surface antigen was detected or the patient had been receiving immunosuppressive therapy. This study did not demonstrate the efficacy of the vaccine in a population of patients receiving dialysis in whom both the rate of antibody response to hepatitis B vaccine and the viral attack rate were low. Other measures to control transmission of hepatitis B virus in dialysis units, including surveillance for hepatitis B surface antigen and isolation of patients who are positive for the antigen, must be continued.

A controlled, randomized, double-blind trial in 1,083 homosexual men from New York confirmed that a highly purified, formalin-inactivated vaccine against hepatitis B prepared from HBsAg positive plasma, is safe immunogenic, and highly efficacious. Over 95% of vaccinated subjects developed antibody against the surface antigen. Vaccine-induced antibody persisted for the entire 24-month follow-up period. The attack rate of all hepatitis B virus infections (excluding conversions of anti-HBc alone) was 3.2% in vaccine recipients compared with 25.6% in placebo recipients (p less than 0.0001). In those who received all three doses of vaccine, of 40 micrograms each, the protective efficacy rate was close to 100%. The vaccine protects against acute hepatitis B, asymptomatic infection, and chronic antigenemia. There is reason to assume that the vaccine is also partially effective when given postexposure.

A method to estimate the thermally induced residual strain accumulation under varying temperature in a Bi2223/Ag/Ag alloy composite superconductor was presented, in which the mechanical property values measured from the stress-strain curves of the samples with different residual strain states, the residual strain value of Bi2223 filaments in the composite tape at room temperature measured by x-ray diffraction and the reported coefficients of thermal expansion of the constituents (Bi2223, Ag and Ag alloy) in the relevant temperature range were incorporated. This method was applied to estimate the change of the residual strain of all constituents of the high critical current type composite tape fabricated by American Superconductor Corporation as a function of temperature. The residual strain value at 77 K estimated by this method and the reported fracture strain of Bi2223 filaments accounted well for the measured strain tolerance of the critical current at 77 K.

We evaluated the efficacy of hepatitis B vaccine (Heptavax-B) containing only the ad subtype in a randomized, placebo-controlled, double-blind trial among 865 staff members of 43 hemodialysis units in the United States. Surface antibody developed in 92.6 per cent of the subjects after two doses of vaccine and in 96 per cent after the six-month booster. The incidence of infections with hepatitis B virus (with or without hepatitis) was 9.9 per cent in placebo recipients and 2.2 per cent in vaccine recipients (P less than 0.01). The two cases of hepatitis B among vaccine recipients did not occur in subjects in whom antibody had developed. In 81 per cent of the hepatitis events, the virus was of the ay subtype. The indicence of ay virus was 8.2 per cent among placebo recipients and 1.2 per cent among vaccine recipients (P less than 0.005). We conclude that these data confirm the efficacy of the vaccine and demonstrate subtype cross-protection.