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Biomedical subjects

A Safary

Publications and source records attributed to A Safary.

At least 55 records · Page 3Linked to original sources
PubMed1993

Brief report: hepatitis A vaccination in Greek military recruits.

Improved standards of sanitation have contributed to a shift in the prevalence of hepatitis A in countries such as Greece. Children are now coming into first contact with the infection at an increasingly later age, leaving more adults susceptible to the disease. In military forces where close living conditions prevail, the likelihood of infection is even more pronounced. An inactivated hepatitis A vaccine has been developed and has been administered successfully to over 24,000 healthy children and adults. This vaccine would be of considerable benefit to military personnel worldwide. The reactogenicity and immunogenicity of a hepatitis A vaccine were evaluated in 200 female military recruits, aged from 17 to 23 years, vaccinated according to a primary vaccination schedule at 0 and 1 months with a booster dose at 6 months. Symptoms reported following vaccination were generally mild and transient. Soreness at the site of injection was the most frequent local symptom and malaise was the most common general symptom. Clinically significant increases in serum liver enzyme levels were not detected. All subjects had seroconverted after the primary vaccination course and maintained anti-HAV titres up to the time of the administration of the booster dose. The booster dose produced more than a tenfold increase in the geometric mean titre (GMT).

Adolescent↗
PubMed1993

Immunogenicity of inactivated hepatitis A vaccine in children.

BACKGROUND: Inactivated hepatitis A vaccine is now becoming available in many countries. METHODS: To evaluate the immunogenicity and safety of inactivated hepatitis A vaccine in healthy children, 99 susceptible schoolchildren from 4 to 15 years of age received 360 enzyme-linked immunosorbent assay units of the inactivated hepatitis A vaccine at months 0, 1, and 6. RESULTS: Antibody to hepatitis A virus seroconversion (> or = 20 mIU/mL) was 97% (96/99) in vaccinees after the first dose and 100% after the second (99/99) and booster (96/96) doses. The geometric mean titers of antibody to hepatitis A virus were 167, 465, and 4133 mIU/mL after each dose of vaccine, respectively. There were no significant side effects during the vaccination. Levels of antibody to hepatitis A virus were also tested in 9 susceptible children at day 7 and months 1 and 4 after the intramuscular injection of 2 mL of immune serum globulin. All children had measurable titers of antibody to hepatitis A virus 1 week after receiving immune serum globulin by sensitive enzyme immunoassay, but measurable titers had disappeared 1-4 months later. CONCLUSIONS: The inactivated hepatitis A vaccine is safe and immunogenic in healthy children.

Adolescent↗
PubMed1993

Simultaneous active and passive immunization against hepatitis A studied in a population of travellers.

Three hundred travellers, seronegative for hepatitis A, were enrolled into this study to evaluate a new inactivated hepatitis A vaccine. Three injections, each containing at least 720 ELISA units, were administered intramuscularly at months 0, 1 and 6. The subjects were distributed into three groups: 100 received vaccine only; 100 received a single injection of immunoglobulin enriched in HAV antibody; and the 100 remaining travellers received the vaccine and immunoglobulin administered simultaneously with the first vaccine dose. In both vaccinated groups, the rate of seroconversion was found to be higher than 90% at month 1, reaching 100% and 97.8% at month 2 in groups 1 and 3, respectively, and 100% at month 7. In the group receiving both vaccine and immunoglobulin, antibody production was somewhat slower and the final titres were, on average, slightly lower than those obtained in the group with the vaccine alone (GMT 2488 and 3614 mIU ml-1 respectively; p = 0.02). The vaccine appeared to be highly immunogenic in all subjects and was also well tolerated. The slight inhibition of antibody production, induced by the concurrent administration of immunoglobulin, does not affect the overall protection afforded by the vaccine. We conclude that simultaneous active and passive hepatitis A immunizations can be recommended.

Adolescent↗
PubMed1993

Characterization of the immune response of volunteers vaccinated with a killed vaccine against hepatitis A.

To characterize the immune response elicited by the hepatitis A virus (HAV) vaccine, the sera of 79 subjects who received two vaccine doses at an interval of 1 month and a booster dose 6 months after the first dose, were analysed by ELISA, radioimmunofocus inhibition test (RIFIT) and by a competition monoclonal antibody assay using two neutralizing mAbs (K3-4C8 and B5-B3), which recognize different epitopes. The data show that 93.6% of the volunteers responded after one dose, as detected by ELISA. After the second dose, 100% seroconversion (total Ig) was achieved and most of the vaccines had neutralizing antibodies. Furthermore, these antibodies are able to inhibit the binding of mAbs K3-4C8 and B5-B3 to the HAV virus, indicating that they recognize two major neutralizing epitopes identified on infectious virions. Using a standard commercial radioimmunoassay test, 100% of the subjects were found positive after the third dose. These different methods of titration were also performed on sera of convalescents and immune serum globulin (ISG) recipients. Although the level of antibodies in convalescents is significantly higher than in vaccinees or in ISG recipients, the relative amount of neutralizing antibodies quantified by the competition monoclonal antibody assay is equivalent for the groups tested.

Adolescent↗
PubMed1993

Safety and immunogenicity of hepatitis A vaccine in healthy children.

The immunogenicity and reactogenicity of an inactivated hepatitis A (HA) vaccine in children were investigated. One hundred three healthy children who lacked antibody to HA virus (anti-HA virus), aged between 3 months and 6 years 8 months, were enrolled in this study. They received three doses of 360 enzyme-linked immunosorbent assay units of HA vaccine in a 0-, 1- and 6-month schedule. Blood tests for aminotransferase and anti-HA virus were performed 7 days before and 1, 6 and 7 months after the first dose. Anti-HA virus was tested by radioimmunoassay and also by enzyme immunoassay for titer determination. The seroconversion rates measured by enzyme immunoassay were 95.1% (98 of 103) at Month 1 and 100% at Months 6 and 7. Nine percent (28 of 309) of the injections were followed by local symptoms, usually mild soreness and swelling at the site of injection, and 12% (37 of 309) by minor general symptoms. We conclude that HA vaccine is highly immunogenic and safe in children. It may replace immunoglobulin as an effective method to prevent HA virus infection in children. We also suggest that the HA vaccine be administered to children in endemic areas.

Alanine Transaminase↗
PubMed1993

Randomized, single-blind comparison of the immunogenicity and reactogenicity of 20 micrograms and 10 micrograms doses of hepatitis B vaccine in adolescents.

The study compares the effect of two different doses of a recombinant DNA hepatitis B vaccine (Engerix-B) administered to 320 healthy adolescents divided randomly into two equal groups, using the 0, 1 and 6 month's vaccination schedule. Initially the larger dose elicited protective levels of antibody in a greater proportion of subjects. The seroprotection rates were significantly higher at both months 1 (17.6% v/s 9.2%) and 2 (68.8% v/s 56.7%). The difference was especially relevant 6 months after the start of the vaccination schedule when a 92.4% seroprotection rate was obtained in the 20 micrograms dose group, whereas only 78.3% of subjects in the 10 micrograms dose group had protective antibody levels. Furthermore there were significant differences in anti-HBs geometric mean titers for seroconverters at months 6 (109 v/s 56mlU/ml) and 7 (4774 v/s 2705mlU/ml). However one month after the third vaccine administration, both doses produced similar high seroprotection rates (97.9% and 97.1%, respectively). The difference in the generally mild overall reactogenicity for the 2 dose levels was not remarkable although the higher dose produced more local symptoms. The conclusion from the study was that the 10 micrograms dose produces a very good antibody response in adolescents, provided the full vaccination course of three doses, according to a 0, 1 and 6 month's schedule, is administered. However, the 20 micrograms dose should be used if compliance to the full course is in doubt since a 92.4% seroprotection rate can be obtained with 2 injections compared to only 78.3% with the 10 micrograms dose.

Adolescent↗
PubMed1992

Clinical trial with inactivated hepatitis A vaccine and recommendations for its use.

OBJECTIVE: To compare the reactogenicity and immunogenicity of an inactivated hepatitis A vaccine in two different immunisation schedules. DESIGN: Randomised trial. SETTING: One London teaching hospital. SUBJECTS: 104 healthy adult volunteers (71 men, 33 women aged 19-60). INTERVENTIONS: Hepatitis A vaccine to group 1 (54 volunteers) at 0, 1, and 2 months and to group 2 (50) at 0, 1, and 6 months. MAIN OUTCOME MEASURES: Symptoms at and after each dose; liver function, hepatitis A virus specific serum immune response; and responses in saliva and parotid fluid in immunised volunteers and subjects with natural immunity. RESULTS: The vaccine was well tolerated; 97% (96/99) and 100% of those immunised developed serum antibody after one and two doses of vaccine respectively. Geometric mean titres increased progressively after each dose and were significantly higher in men but not women in group 2 after the third dose (ratio between geometric mean titres 0.265, 95% confidence interval 0.18 to 0.39; p less than 0.001). At one year this group-sex interaction was absent; geometric mean titres for both sexes were significantly higher in group 2 (ratio 0.330, 0.227 to 0.478; p less than 0.0001). Antibody responses were not significantly different between the groups at two years. Compared with naturally infected subjects immunised volunteers developed poor or undetectable virus specific IgG and IgA responses in saliva and parotid fluid. CONCLUSIONS: The vaccine was safe and highly immunogenic, and the differences in the immune responses in saliva and parotid fluid are unlikely to affect its efficacy.

Adult↗
PubMed1992

Heat stability of a recombinant DNA hepatitis B vaccine.

The heat stability of a recombinant DNA hepatitis B vaccine was studied in healthy adult volunteers. When compared with vaccine stored at 4 degrees C, heating of the vaccine for 1 week at 45 degrees C or for 1 month at 37 degrees C did not alter the reactogenicity or the ability of the vaccine to elicit antibody titres considered to be protective. These results have significance in situations where the cold chain is broken, as can happen in countries where proper storage and transport facilities are not always available.

Adolescent↗
PubMed1992

Effect of virus strain and antigen dose on immunogenicity and reactogenicity of an inactivated hepatitis A vaccine.

A randomized double-blind comparison of five killed hepatitis A vaccine preparations was carried out with eligible medical student and staff volunteers. Vaccines were prepared in M RC-5 cells and formalin-inactivated. Three monthly injections of 1 ml in the deltoid muscle were given. Group A received the CLF strain at a dose of 360 ELISA units (El.U) in 0.5 mg aluminium hydroxide (n = 35). The other groups received the HM175 strain as follows: 180 El.U in 1 mg aluminium hydroxide (to group B, n = 42), 360 El.U in 0.5 mg aluminium hydroxide (to group C, n = 40), 360 El.U in 1 mg aluminium hydroxide (to group D, n = 39) and 720 El.U in 1 mg aluminium hydroxide (to group E, n = 43). The geometric mean anti-HAV concentration (GMC) measured in mIV/ml by an ELISA method one month after each injection were: group A, 223, 480, 1635; group B, 123, 221, 649; group C, 185, 365, 1085; group D, 144, 323, 1076; group E, 229, 646, 2521. At month 6, the GMC had fallen by approximately 20%. Seroconversion as measured by ELISA was 100% in groups A and E after one injection, and 100% in all groups after three injections; after two injections, only one subject in group C was still negative. The dose effect with HM175 vaccine was significant. There was a good correlation between ELISA and neutralization (radioimmunofocus inhibition test) titres. One month after the second dose, all subjects in groups A and E had both hepatitis A virus immunoglobulin M (HAV IgM) geometric mean titre, (GMT > 5000) and IgG (GMT > 25,000) as measured by a sensitive terminal dilution ELISA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Effect of hepatitis A vaccination schedules on immune response.

An inactivated hepatitis A vaccine was given to 104 seronegative volunteers aged between 19 and 60 years according to two schedules: 0, 1 and 2 months or 0, 1 and 6 months. The vaccine was well tolerated and 97 and 100% of vaccinees developed a serum antibody response following a single and two doses of vaccine respectively. Geometric mean titres increased progressively after each dose; responses following the 0, 1, 6 month schedule were significantly higher at one year but, among those tested at two years, these differences were less marked. Vaccinees, when compared with naturally infected persons, developed poor or undetectable hepatitis-A-virus-specific immunoglobulin G and A antibody responses in saliva and parotid fluid. Such differences are, however, unlikely to affect the protective efficacy of the vaccine.

Adult↗
PubMed1992

Persistence of vaccine-induced antibody to hepatitis A virus.

A level of 10 mIU hepatitis A antibodies/ml as measured by ELISA is believed to be the minimal protective concentration. If this level is considered, the mean persistence of vaccine induced antibodies is approximately 10-11 years after booster dose, 6-7 years if only the primary doses are given and 5-6 years if the minimal individual titre is taken into account.

Enzyme-Linked Immunosorbent Assay↗
PubMed1992

Simultaneous passive and active immunization against hepatitis A.

The serum antibody response to simultaneous administration of immune globulin (Ig) and an inactivated hepatitis A vaccine was investigated in healthy volunteers who had been tested and found free of hepatitis A virus. One hundred and forty nine subjects were randomly allocated into three groups. Group 1 received three doses of hepatitis A vaccine at 0, 1 and 6 months, group 2 received 5 ml of Ig and group 3 received a combination of Ig and vaccine. In group 3 the seropositivity rate measured by enzyme-linked immunosorbent assay was 100% at day 5, month 1 and 2, 96% at month 6 and again 100% at month 7. In the group that received vaccine alone the seroconversion rates were 0, 96, 100, 98 and 100 respectively. The geometric mean titres in subjects who received passive/active immunization were about twofold lower than in subjects who received vaccine alone, indicating interference of Ig with the immune response. Despite this, the data show that simultaneous administration of hepatitis A vaccine and Ig confers both immediate protection via Ig administration and long-term vaccine-induced protection. As the antibody levels reached are about twofold lower compared to that after administration of hepatitis A vaccine alone, a booster dose may be required sooner, than if the vaccine were administered alone.

Adult↗
PubMed1992

Simultaneous vaccination against hepatitis A and B: results of a controlled study.

Hepatitis A and hepatitis B are endemic in many countries and must be considered as serious health risks for large parts of the world population. Simultaneous or combined vaccination against these two diseases would therefore be most advantageous. In order to investigate possible interactions between these vaccines with respect to their tolerability and immunogenicity, we conducted a randomized prospective study comparing single and simultaneous administration of the two vaccines. Three groups of healthy volunteers, each with 55 persons, were included in the study. All were negative for hepatitis A and hepatitis B markers and had normal serum liver enzyme values. Group I received hepatitis A vaccine (720 ELISA units) into the left deltoid muscle, group II received hepatitis B vaccine (20 micrograms) into the right deltoid muscle and group III received hepatitis A vaccine into the left, and hepatitis B vaccine into the right deltoid muscle. Three doses of the vaccines were administered at 0, 1 and 6 months. Local and systemic reactions were monitored by means of questionnaires. Blood samples for determination of antibody to hepatitis A virus (anti-HAV) and antibody to hepatitis B surface antigen (anti-HBs) and of serum SGOT and SGPT levels were drawn at months 0, 1, 2, 6 and 7. There were no serious general and only mild local reactions. The mean serum SGOT and SGPT values remained in the normal range in all groups. The seroconversion rates and mean geometric titres of the anti-HAV and anti-HBs antibodies were similar when the vaccines were administered separately or simultaneously. There were no significant differences between the compared groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Clinical assessment of the safety and efficacy of an inactivated hepatitis A vaccine: rationale and summary of findings.

The objectives for the clinical testing of the inactivated hepatitis A vaccine developed by SmithKline Beecham Biologicals are reviewed and the results obtained are summarized. The first studies were carried out in healthy young adult volunteers using pilot vaccine lots prepared from the CLF and HM175 strains of hepatitis A virus (HAV). It was established that the candidate vaccines were well-tolerated, caused no hypersensitivity reactions and elicited a strong antibody response. As the yield in production with the HM175 strain was higher it was preferred over the CLF strain for further development of a vaccine. A dose-range study with HM175 vaccine in adults showed that an antigen dose of 720 ELISA units (El.U) produced almost 100% seroconversion after one injection. This dose was therefore chosen as appropriate for adults. A dose of 360 El.U was used in children. To date, a total of 67 studies in 18 countries involving 47,145 subjects, including 20,586 control subjects, have been initiated. In these studies, 55,259 doses of HM175-derived hepatitis A vaccine have so far been administered. This extensive experience has shown that the vaccine is well-tolerated, causing essentially only mild, transient local reactions. Vaccine reactogenicity was assessed using symptom checklists, filled in by the volunteers or their parents, for a period of 4 days following vaccination. Blood samples were obtained at different times after vaccination to evaluate the immune response. Clinical studies with six different lots, manufactured using commercial-scale production methods, have been carried out on 2901 adults. These studies have shown that a seroconversion rate of 95.7% (1225/1280) is obtained one month after the first vaccine dose.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long term efficacy of hepatitis B vaccine in infants born to hepatitis B e antigen-positive mothers.

The long term protective efficacy of recombinant hepatitis B vaccine, administered alone or concomitantly with hepatitis B immunoglobulin, was assessed in 263 healthy neonates of hepatitis B e antigen-positive mothers. Infants received the first dose of vaccine at birth; additional doses were given at either Months 1, 2 and 12 or Months 1 and 6. During the follow-up period, which ranged from 2 to 4 years, protective titers (> or = 10 mIU/ml) of anti-hepatitis B surface antibodies were found in virtually all infants who had responded to the primary course of vaccination. "Natural boosts," without persistent infection, were observed in only a small number of children. All children who were shown to have become chronic carriers were infected within the first year of life. No statistical difference in long term protective efficacy could be shown between the two vaccination schedules used or between the use of vaccine alone or vaccine plus hepatitis B immunoglobulin for either schedule.

Cohort Studies↗
PubMed1991

The protective efficacy of recombinant hepatitis B vaccine in newborn infants of hepatitis B e antigen-positive-hepatitis B surface antigen carrier mothers.

Recombinant hepatitis B vaccine has been shown to be as safe and effective as plasma-derived vaccines. However, its efficacy in the prevention of perinatal infection has not been fully evaluated in an endemic area. We recruited 110 high risk infants born to hepatitis B e antigen-positive-hepatitis B surface antigen (HBsAg) carrier mothers in a study of recombinant vaccine efficacy. They were randomized into 2 groups, A (54 infants) and B (56 infants), to receive 4 doses of vaccine, containing 20 or 10 micrograms of surface antigen, respectively, at 0, 1, 2 and 12 months of age. An additional 60 high risk infants were recruited later (Group C) and received three 20-micrograms doses of vaccine at 0, 1 and 6 months of age. All infants also received a dose (145 IU) of hepatitis B immunoglobulin soon after birth. Sera were collected at 0, 1, 2, 3, 6, 12 and 14 months of age to assay HBsAg and anti-HBs. At 12 months of age the HBsAg carrier rates were 7.4 and 1.8%, in Groups A and B, respectively. In Group C the HBsAg-positive rate was 3.3%. HBsAg was invariably first observed between 0 and 2 months of age. Virtually all noncarrier infants developed substantial titers of anti-HBs at 12 months of age. No serious adverse effect was observed after vaccination.

Carrier State↗
PubMed1990

Safety and immunogenicity of an inactivated hepatitis A candidate vaccine in healthy adult volunteers.

The reactogenicity and immunogenicity of a formaldehyde-inactivated hepatitis A vaccine have been investigated. Three different dose levels of vaccine (180, 360 and 720 ELISA units) were administered to healthy volunteers according to a 0, 1, 2 and 12 month schedule. The vaccine was safe and well tolerated. Reactions observed following vaccination were essentially mild and were not dependent upon the quantity of antigen administered. All subjects had measurable titres of anti-HAV antibodies after the full vaccination course; the immune response to the vaccine was dose-related. Antibody titres in vaccinees at month 13 were between 60- and 190-fold higher than those observed in a group of subjects given anti-HAV immunoglobulin.

Adolescent↗