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Biomedical subjects

A Safary

Publications and source records attributed to A Safary.

At least 73 records · Page 4Linked to original sources
PubMed1989

Protective efficacy of a recombinant deoxyribonucleic acid hepatitis B vaccine in institutionalized mentally handicapped clients.

Mentally handicapped clients in institutions are at high risk for hepatitis B virus (HBV) infection. In 1985, 770 mentally handicapped residents from four institutions in the Antwerp area were screened for HBV markers. The prevalence of hepatitis B surface antigen was 10.3 percent (range, 6.1 to 15.2 percent); 42.3 percent (range, 11.5 to 60.1 percent) had antibodies to hepatitis B surface antigen and the hepatitis B core antigen. In 1986, 275 seronegative mentally handicapped residents were vaccinated intramuscularly in the deltoid region with 20 micrograms (1.0 ml) of a recombinant deoxyribonucleic acid yeast-derived hepatitis B vaccine (Engerix-B, SmithKline Biologicals, Rixensart, Belgium) on a zero-, one-, six-month schedule. Serum samples were collected at Months 1, 2, 7, 12, and 24 and were tested for HBV markers by radioimmunoassay. The seroconversion rates for hepatitis B surface antigen antibodies were 39 percent at Month 1 (geometric mean concentration, 6.4 IU/liter), 82 percent at Month 2 (geometric mean concentration, 23.4 IU/liter), 97 percent at Month 7 (geometric mean concentration, 1,034 IU/liter), and 96 percent at Month 12 (geometric mean concentration, 269 IU/liter). Among the 214 residents evaluated at Month 12, 69 percent had hepatitis B surface antigen antibody levels greater than 100 IU/liter (geometric mean concentration, 603 IU/liter). No significant adverse reactions were observed. Within the first seven months of observation, HBV infection was detected in eight of 271 subjects (estimated annual incidence of 5 percent). During this period, none of the clients developed clinical hepatitis or showed biochemical evidence of liver damage. Between eight and 24 months, no additional HBV infections were detected. These data can be compared with an annual incidence of HBV infection of 8.7 percent in a historical cohort of mentally handicapped residents in one of the four institutions.

Adolescent↗
PubMed1989

Protective efficacy of a recombinant DNA hepatitis B vaccine in neonates of HBe antigen-positive mothers.

We have assessed the protective efficacy of a recombinant DNA hepatitis B vaccine alone in infants of women who were positive for the surface antigen and the e antigen. The infants received a 10-micrograms dose of the vaccine within 12 hours of birth and additional doses 1, 2, and 12 months later. No significant adverse reactions to vaccination were observed and the vaccine was highly immunogenic. Only 2 (3.6%) of the 55 infants followed up to 13 months became chronically infected with the hepatitis B virus, as evidenced by the persistent presence of hepatitis B surface antigen in serum samples. Without immunoprophylaxis, 65% to 90% of such infants would become chronic carriers. Immunization with a recombinant vaccine without concomitant administration of hepatitis B immunoglobulin, therefore, considerably decreased the incidence of the carrier state.

Carrier State↗
PubMed1988

Lack of induction of IgE and IgG antibodies to yeast in humans immunized with recombinant hepatitis B vaccines.

Yeast-derived hepatitis B vaccines (partially purified or highly purified) at different dosages and a plasma-derived hepatitis B vaccine (control) were injected into 50 young volunteers 3 times at monthly intervals. Before and 4 weeks after this series of immunizations, blood samples were drawn and tested for presence of IgE and IgG antibodies against yeast antigens. No rise in IgE antibodies against Saccharomyces cerevisiae antigens nor in IgG antibodies against Candida albicans antigens was found. Together with former clinical results this underlines the experience that type I and type III reactions against putative yeast contaminants apparently play no major role after immunization with recombinant hepatitis B vaccines.

Adult↗
PubMed1987

Clinical development of a new recombinant DNA hepatitis B vaccine.

The clinical development plan for the new recombinant DNA yeast-derived hepatitis B vaccine manufactured by SmithKline Biologicals is summarized. Initially, the emphasis was on assessing the risk of hypersensitivity to yeast-derived contaminants. This was followed by an evaluation of local and general reactions after vaccination. Next, the optimal dose of vaccine to be administered was ascertained followed by an evaluation of the efficacy of different vaccination schedules. The reactogenicity and immunogenicity of the yeast-derived vaccine was compared with that of two commercially available plasma-derived vaccines. The recombinant vaccine's protective efficacy was assessed in chimpanzees and by comparing attack rates in historical homosexual control groups with those in vaccinated homosexuals. Ongoing studies are investigating the protection of neonates born to HBeAg-positive carrier mothers.

Antigens↗
PubMed1987

Reactogenicity and immunogenicity of different lots of a yeast-derived hepatitis B vaccine.

Several lots of a yeast-derived hepatitis B vaccine at different doses and a 20 micrograms dose of plasma-derived vaccine were tested in young healthy adults and compared with respect to risk of hypersensitivity reactions, reactogenicity, and immunogenicity. No signs of hypersensitivity either pre-existing or vaccine-induced were observed. Reactogenicity was low and similar in all vaccine groups. It was not dose related and unaffected by the number of injections. Immunogenicity was evaluated for a 0, 1, 2, and 12 month vaccination schedule. Seroconversion rates (greater than or equal to 10 IU/l) were not significantly different between the purified yeast- and plasma-derived vaccines one month after the second vaccination whereas the percentage of seroconversion was slightly lower in the groups receiving only partly purified recombinant vaccines. Although geometric mean titres induced by the plasma-derived vaccine were somewhat higher after the first months, the antibody titres induced by the recombinant vaccine were at least as high as those elicited by a plasma-derived vaccine following the booster dose.

Antigens↗
PubMed1987

Persistence of vaccine-induced antibodies to hepatitis B surface antigen and the need for booster vaccination in adult subjects.

Protection against hepatitis B virus infection can be achieved by the induction of neutralizing antibodies against the hepatitis B surface antigen (HBsAg). An antibody concentration of 10 IU/l, as measured by radioimmunoassay, is considered to be protective. HBsAg can be produced either from the plasma of chronic carriers or by DNA recombinant technology in yeast cells. Plasma- and yeast-derived vaccines have been compared in several studies and their immunological properties were found to be similar, including the persistence of antibodies induced by either type of vaccine. Finally, yeast-derived hepatitis B vaccine can boost anti-HBs responses initially elicited by either plasma- or yeast-derived vaccine equally and effectively. In order to maintain protective immunity after hepatitis B vaccination, antibody determination and, if necessary, booster vaccination should be performed, particularly in high-risk persons.

Adult↗
PubMed1987

Immunogenicity of a recombinant DNA hepatitis B vaccine in neonates.

Infants of HBsAg-positive mothers (Group I) as well as those born to women without HBV markers (Group II) were vaccinated with a 10 micrograms dose of a recombinant DNA hepatitis B vaccine within 24 hours after birth according to a 0, 1, and 2 month schedule, with a booster dose planned 12 months later. Vaccination results in 14 (Group I) and 47 (Group II) neonates showed that at two months after the third dose of vaccine, 86% (6/7) and 100% (37/37), respectively, seroconverted, with anti-HBs geometric mean titres of 80 IU/l and 266 IU/l in the respective groups. No adverse reactions to the vaccine were observed. These preliminary results indicate that the recombinant DNA hepatitis B vaccine is safe and highly immunogenic in newborns.

Antigens↗
PubMed1987

Immunogenicity and tolerance of a yeast-derived hepatitis B vaccine in homosexual men.

A yeast-derived recombinant DNA vaccine against hepatitis B was administered to 314 active homosexual men lacking serum markers for hepatitis B virus. Volunteers were vaccinated intramuscularly in the deltoid region at 0, 1, and 6 months with either a 20- or 40-micrograms dose per injection. Serologic tests for syphilis and human immunodeficiency virus were positive in 3.2% and 2.0%, respectively. The overall seroconversion rates for anti-HBs were 35%, 97%, and 98% after the first, second, and third injection, respectively. The geometric mean titres of anti-HBs antibodies at 7 months were 955 IU/l and 2541 IU/l, for the 20 and 40 micrograms doses, respectively. Among 183 completely vaccinated subjects, 97% had an anti-HBs titre greater than 10 IU/l. Tolerance of the vaccine was excellent. Among the 183 subjects followed up for at least 7 months, two volunteers developed HBsAg and anti-HBc within one month of the first vaccine injection and one anti-HBc just before the third dose of vaccine. However, no subject experienced clinical hepatitis or ALT elevations.

Adolescent↗
PubMed1987

Vaccination of newborns of HBsAg-positive carrier mothers with a recombinant DNA hepatitis B vaccine.

Thirty neonates born to HBsAg-positive mothers were vaccinated with a 20 microgram dose of the SmithKline Biologicals recombinant DNA yeast-derived vaccine within 24 hours after birth, with similar inoculations repeated 1 and 2 months later. Preliminary results indicate that the recombinant vaccine was well tolerated and immunogenic. A 100% seroconversion rate was achieved 4 months after the first vaccine dose and the anti-HBs geometric mean titres progressively rose from 14 to 31,279 and 361 IU/l at months 1, 2, 4, and 6, respectively. Although a longer period of observation and comparison with a historical control group are needed to evaluate its protective efficacy in this high-risk population, the fact that no vaccinated newborns have been infected is encouraging.

Antigens↗
PubMed1987

Summary of clinical findings on Engerix-B, a genetically engineered yeast derived hepatitis B vaccine.

Between February 1984 and August 1986 results have been obtained in 58 completed or ongoing clinical studies by 33 investigators in 19 countries on a yeast-derived recombinant DNA hepatitis B vaccine (Engerix-B). Among the 6100 subjects enrolled in these studies, 5664 subjects (150 normal neonates, 178 neonates of hepatitis B carrier mothers, 330 children aged 3-10 years, 3697 young healthy adults, 438 homosexual males, 110 older healthy adults, 139 drug addicts, 262 institutionalized mentally retarded patients, 59 thalassaemics, 25 sicklaemics, 270 patients on chronic haemodialysis and 6 haemophiliacs) received one or more (up to 4) injections of different doses of the yeast-derived vaccine according to either a 0, 1, 2, and 12 month or a 0, 1, and 6 month vaccination schedule. In randomized comparative studies 436 subjects received either one of two commercially available plasma-derived vaccines. The results reviewed in the present summary have shown that Engerix-B is safe, clinically well tolerated, gives an anti-HBs response which is qualitatively and quantitatively similar to that obtained with plasma-derived vaccines and confers protection against infection and disease. Engerix-B can be considered as a valid alternative to existing hepatitis B vaccines.

Adult↗
PubMed1986

Placebo controlled pneumococcal immunization in patients with bronchogenic carcinoma.

Pneumococcal vaccine [heptadecavalent types 1, 2, 3, 4, 6A, 7F, 8, 9N, 11A, 12F, 14, 15F, 17F, 18C, 19F, 23F and 25 pneumococcal capsular polysaccharide vaccine (Moniarix)] or placebo were evaluated in 26 and 21 patients with bronchogenic carcinoma, most of whom did not receive prior radiotherapy or chemotherapy. No difference was detected as far as clinical outcome is concerned: 3 vaccinated patients out of 26 (11.5%) developed pneumococcal infections (1 fatal bacteremia) and 4/21 (19%) of those who received a placebo presented such an infection (1 fatal bacteremia). The antibody response was significantly increased in the vaccines for types 1, 2, 7F, 8, 9N, 12F, 14, 17F, 18C, 23F and 25.

Adult↗
PubMed1985

Evaluation of two tetravalent (ACYW135) meningococcal vaccines in infants and small children: a clinical study comparing immunogenicity of O-acetyl-negative and O-acetyl-positive group C polysaccharides.

Two different tetravalent polysaccharide vaccines against group A, C, Y, and W135 meningococci were given to 118 infants aged 6 to 23 months; the same vaccines were administered in a second dose 12 months later to those infants aged 6 to 11 months at first vaccination. Forty of the infants received vaccine containing the nonacetylated group C polysaccharide C(OAc-) and 78 the acetylated group C polysaccharide C(OAc+) together with group A, Y, and W135 polysaccharides. All polysaccharides, at a dose of 30 micrograms, induced antibody responses after administration of both vaccines in all age groups although the responses were better in the older infants. Acetylation of the sialic acid of the group C polysaccharide did not significantly influence the response. Rapid decreases in the antibody titers after the first vaccination stressed the need for one or more revaccinations. Vaccination elicited mild local and systemic reactions. Elevated temperatures were more common in the youngest infants but only four developed fever exceeding 38.5 degrees C (101.3 degrees F). We conclude that tetravalent (ACYW135) meningococcal vaccine is safe and immunologically effective in children younger than age 2 years. However, revaccinations may be required to maintain immunity.

Age Factors↗