G. Renzulli

Persistence of anti-HBs antibodies in health care personnel vaccinated with plasma-derived hepatitis B vaccine and response to recombinant DNA HB booster vaccine

Long-term persistence of specific antibodies after primary immunization against HBV infection has been reported. In this study, we evaluated the persistence of anti-HBs in vaccinees 6 years after primary immunization and the response to a booster dose using a recombinant DNA yeast-derived HB vaccine. An 85.4% seroprotection rate was observed after 6 years with a significantly higher seroprotective rate in those subjects who received four doses of vaccine primary immunization as compared with those who received three doses (93.9% versus 67.2%, p < 0.001). One month after receiving the booster dose, 98.6% of the subjects had an anamnestic type of response. The GMTs were found to decrease progressively with increasing age. The antibody levels after booster dose were higher than those attained at the end of primary immunization and reflected the trend seen before the administration of the booster. These results are consistent with the existence of an effective immunological memory in HB vaccine responders. Subjects who received four doses during primary immunization were better seroprotected and had a higher seroprotection rate after the booster dose.

Two different dosages of yeast derived recombinant hepatitis B vaccines: a comparison of immunogenicity

The efficacy of a 10 or 20 micrograms antigen load of HB recombinant vaccines is still being debated. A comparison of anti-HBs titres in two groups of healthy subjects vaccinated by the same schedule (0, 1 and 6 months) employing recombinant HB vaccines with different antigen loads, 20 micrograms (group A, 251 subjects) and 10 micrograms (group B, 256 subjects) was carried out. A seroprotection rate of 99.6 and 99.2% was observed for group A and group B, respectively, at the end of primary immunization. No statistically significant difference in seroprotection rate was observed. Group A showed significantly higher GMTs than group B for all age groups and for both sexes except for males above 25 years. The difference was more marked for younger age groups and for the female sex. These data support the higher immunogenicity of vaccine with 20 micrograms antigen load as compared to vaccines with 10 micrograms antigen load.

Response to an Extra Dose of Hepatitis B Vaccine and Specific Antibody Persistence in Non-Responders to Primary Immunization

BACKGROUND In a campaign to vaccinate health care workers, a three-dose schedule (0, 1, and 6 months) and a four-dose schedule (0, 1, 2, and 14 months) with hepatitis B (HB) vaccine were used. After primary immunization 26 subjects vaccinated with the 3-dose schedule and 4 subjects vaccinated with the 4-dose schedule had undetectable anti-HBs titres. METHODS All these 30 non-responders received an extra dose of the same vaccine 2 months after primary immunization and a booster dose with a yeast-derived vaccine 6 years later. Anti-HBs levels were evaluated 1 month after the extra dose and after the booster dose. RESULTS One month after the extra dose 26.9% (7 of 26) of the subjects vaccinated with the 3-dose schedule became positive for anti-HBs. Six years later only two of these subjects had detectable anti-HBs. After the booster dose the seven subjects who responded to the extra dose showed an anamnestic type of response, and five additional subjects became positive for anti-HBs. Responders to the extra dose were significantly younger than the non-responders. In the four-dose group only one subject responded to the extra dose, and that subject maintained protective anti-HBs. CONCLUSION About 25% of non-responders to primary HB vaccination could benefit from an extra dose, and these subjects show an anamnestic type of response to HBs antigen even after 6 years. This response seems to be influenced by age.

Response to HBV vaccine in relation to anti-HCV and anti-HBc positivity: a study in intravenous drug addicts

Drug addicts represent the group of young adults with the lowest response to hepatitis B virus (HBV) vaccine. A study was carried out on 110 current intravenous heroin users attending the service providing assistance to intravenous drug users (IVDUs) (SERT) in Padua: 66.4% of them were found anti-hepatitis C virus (HCV)-positive and 33.6% were anti-HBc positive; 29.9% were positive for both. The subjects were vaccinated with 10 microg of yeast-derived vaccine at months 0, 1 and 2 (fast schedule). The overall response rate was 66.4%. Response seems to be affected by positivity to anti-HBc, but not to HCV infection.

Epidemiological aspects of tuberculosis in the Padua Health District 1985-1996.

The present study was carried out in order to monitor the epidemiology of Mycobacterium tuberculosis disease in the Padua Health District over the period 1985–1996 with a view to the situation in some population subgroups. The average annual rate per 100,000 persons per year was 7.9 with a peak in 1994 (15.6 per 100,000 persons). The most significant variations are not per annum but between the periods 1985–1990 and 1991–1996 (average rates per 100,000 persons: 4.8 and 10.9, respectively). The trend shows an increasing frequency in all age groups and especially among the elderly. Immigration from endemic areas and human immunodeficiency virus (HIV) infection appear to contribute to the increase the number of notified cases among adults. In the last four years an increase of tuberculosis cases was also observed among subjects with professional exposure risk. Improvements of programs both at national and regional level are believed to be essential to the tuberculosis control.