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B Yvonnet

Publications and source records attributed to B Yvonnet.

At least 37 records · Page 2Linked to original sources
PubMed1986

Seven-year study of hepatitis B vaccine efficacy in infants from an endemic area (Senegal).

A booster dose of hepatitis B vaccine was given to 143 children in whom hepatitis B had not developed 1 year after initial vaccination. Over the next six years the incidence of hepatitis B in this group was 1.5% per year compared with 11.5% per year in a similar group of unvaccinated children. In the first 4 years the protective efficacy of the vaccine was 100%, but during the 5th and 6th years it fell to 67%. For maximum protection a second booster is needed, 5 years after the first.

Carrier State↗
PubMed1986

Simultaneous administration of hepatitis B and yellow fever vaccines.

In most developing countries, hepatitis B prevention is carried out early in life. In these countries, mobile immunization teams have a limited number of sessions to devote to each rural community; simultaneous administration of multiple antigens is thus normal practice. We compared the immune responses of Senegalese children to the separate or simultaneous injections of yellow fever and hepatitis B vaccines. Injections were given at the time of booster injection for hepatitis B vaccine. Yellow fever antibodies were detected in similar proportions in infants immunized with either yellow fever vaccine alone or yellow fever and hepatitis B vaccines simultaneously. However, a lower proportion of high yellow fever antibody levels were observed when the two vaccines were injected simultaneously. No reduction in the anamnestic response of antibodies against the surface antigen of hepatitis B virus (anti-HBs) was observed when yellow fever vaccine was injected at the same time as the booster dose of hepatitis B vaccine. Since no untoward reactions were noted, it is concluded that hepatitis B and yellow fever vaccines can be administered at the same time.

Antibodies, Viral↗
PubMed1986

Simultaneous administration of diphtheria-tetanus-pertussis-polio and hepatitis B vaccines in a simplified immunization program: immune response to diphtheria toxoid, tetanus toxoid, pertussis, and hepatitis B surface antigen.

We studied the interactions of hepatitis B vaccine with other vaccines used in the World Health Organization expanded programs of immunization. Three groups of Senegalese children were vaccinated with hepatitis B vaccine (HB) alone, diphtheria-tetanus-pertussis (DTP)-polio vaccine alone, or a combination of hepatitis B vaccine and DTP-polio vaccines simultaneously. The immune responses to HBsAg, tetanus toxoid, diphtheria toxoid, and pertussis were measured after one and two vaccinations at 6-month intervals. The immune responses to the combination of HB vaccine and DTP-polio vaccines were similar to the immune responses observed after administration of each vaccine alone. In addition, no adverse reactions were noted. These experimental trials also demonstrated that with a DTP-polio vaccine containing 30Lf of tetanus and diphtheria toxoids, two doses given at 6-month intervals are sufficient to provide a satisfactory immune response. In the case of pertussis and HB vaccines; however, a third dose is necessary.

Antibodies, Bacterial↗
PubMed1986

Lack of adjuvant effect of the pertussis component on IPV DTP-polio vaccine in children.

On day 0, four groups of children (3 to 6 months old) randomly received IPV alone or IPV + pertussis, or IPV + DP, or IPV + DTP. At days 28 and 56, all the children received the same IPV + DTP vaccine. Polio neutralizing and diphtheria antibodies were determined at days 0, 28 and 56. No adjuvant and even some inhibitory effect of pertussis was observed at days 28 and 56 on mean polio antibody titers. These results are compared to those observed with diphtheria.

Adjuvants, Immunologic↗
PubMed1986

Simultaneous administration of diphtheria/tetanus/pertussis/polio vaccine and hepatitis B vaccine in a simplified immunization programme.

In most developing countries hepatitis B virus is endemic and prevention has to be carried out early in life and on a mass scale. In these regions, simultaneous administration of multiple antigens is normal practice. We have therefore, investigated the interaction of hepatitis B vaccine with DTP-Polio vaccine. Studies include the immune response post one and two injections to diphtheria and tetanus toxoid, pertussis and hepatitis B surface antigen. The vaccines were given simultaneously or not at a 6 months interval. The immune response to HBsAg vaccine and DTP-Polio vaccine injected simultaneously was equal to the immune response observed after administration of vaccines alone. Moreover, no adverse reactions were noted. This trial also demonstrated that immunization with two doses of DTP-Polio vaccine, containing 30 Lf of diphtheria and tetanus toxoids, at a 6 months interval is sufficient to obtain a very good immune response.

Antibodies, Bacterial↗
PubMed1986

Simultaneous administration of hepatitis B and yellow fever vaccines.

In most developing countries, hepatitis prevention has to be carried out early in life and on a mass scale. In such countries, mobile immunization teams have a limited number of sessions to devote to each rural community ans simultaneous administration of multiple antigens is normal practice. We have, therefore, compared the immune response to yellow fever and hepatitis B vaccines when injected simultaneously or not to Senegalese children. Injections were done at time of booster injections for hepatitis B vaccine. Yellow fever antibodies were detected in a similar proportion in infants immunized with yellow fever vaccine. However, a lower proportion of high yellow fever antibody levels was observed when the two vaccines were injected simultaneously. No reduction in the anti-HBs anamnestic response was observed when yellow fever vaccine was injected at the same time as the booster dose of hepatitis B vaccine. As no untowards reactions were noted, it can be concluded from the results that hepatitis B vaccine and yellow fever vaccine could be injected at the same time.

Antibodies, Viral↗
PubMed1986

Persistence of circulating complexes between HBsAg and immunoglobulin M in sera of hepatitis B surface antigen positive patients suffering from liver cirrhosis or primary liver cancer.

Complexes between hepatitis B surface antigen (HBsAg) and immunoglobulin M (IgM) have been detected in acute type B hepatitis. Sequential serum testing for the presence of these complexes has been shown to be the best method for predicting disease chronicity. The presence of HBsAg/IgM complexes was investigated using an enzyme-linked immunosorbent assay with selected sera from Senegal. The three population groups studied were composed of 405 Senegalese soldiers as well as 84 liver cirrhosis and 169 primary liver cancer patients. Only one of the 122 HBsAg negative sera tested was found to be positive for HBsAg/IgM complexes. Complexes were detected 13.9% of the HBsAg positive soldiers, in 40% of the HBsAg positive liver cirrhosis patients, and in 50% of the HBsAg positive primary liver cancer patients. HBsAg/IgM complexes were also detected in 53.6% of the hepatitis B e antigen (HBe) positive soldiers, compared to 75 and 76% for the HBeAg positive liver cirrhosis and primary liver cancer patients, respectively. In anti-HBe positive sera, an increased proportion of HBsAg/IgM complexes was observed during the sequence chronic hepatitis (5%)-cirrhosis (29%)-primary liver cancer (42%). On the other hand, it has been reported that in the sequence of events leading from chronic hepatitis to primary liver cancer, there is an increase in anti-HBeAg prevalence and in alpha-fetoprotein levels. In this study, only alpha-fetoprotein levels were found to increase. Values higher than 15 IU/ml were observed in 4.3, 27.3, and 86.4% of the HBsAg positive individuals from the three groups. No significant variation was observed in the anti-HBe prevalence between the population group (64-75%).

Antigen-Antibody Complex↗
PubMed1985

[Hepatitis B and primary cancer of the liver in intertropical Africa].

During the past 15 years, a growing body of evidence incriminates hepatitis B virus as the major factor in the etiology of primary liver cancer. Epidemiological studies throughout the world reported a striking correspondence between areas where the frequency of primary liver cancer is high and where HBV infection is hyperendemic. Moreover, primary liver cancer is commonly associated with cirrhosis of the postnecrotic macronodular type. Such data suggested a sequence hepatitis-cirrhosis-PLC. Such sequence was confirmed by extensive serologic testing studies which reported a high frequency of HBV markers in PLC patients compared to matched control groups. Data collected in Senegal, Mali and Burundi on 12,000 individuals stress the importance of HBV infections in these countries, as the high rate of chronic carrier state in patients suffering from liver cirrhosis or primary liver cancer (62-63%) compared to the general population (12-17%). Other HBV markers including anti-HBs, anti-HBc, HBeAg and anti-HBe had no prognostic value in the sequence hepatitis-cirrhosis-PLC. A new HBV seric marker, the HBsAg/IgM complexes, observed in HBsAg positive individuals, is more frequently detected in PLC patients (50%) and cirrhosis (40%) than in healthy HBsAg carriers (14%). These results would indicate that HBsAg carriers are more likely to develop cirrhosis or primary liver cancer when they evidence HBsAg/IgM complexes. In conclusion, the seric markers of evolution towards primary liver cancer are: HBsAg (the highest known risk factor), the presence in such individuals of HBsAg/IgM complexes, and increased values of alphafoetoprotein.

Adolescent↗
PubMed1984

Immunogenic effect of hepatitis B vaccine in children: comparison of two- and three-dose protocols.

The immunogenic effect of hepatitis B vaccine was evaluated in 183 seronegative infants from Senegal. Seventy-two seronegative infants received two 5-micrograms doses of vaccine at a two-month interval and 111 seronegative infants received three 5-micrograms doses at one-month intervals. All the children had a booster dose one year after the first injection of vaccine. No difference between the two groups was observed in the seroconversion rate (93.1% and 94.6%, respectively); in the proportion of high anti-HBs titer; or in the anti-HBs geometric mean titer (82 and 92 mIU/ml, respectively). These results demonstrate that two doses of 5 micrograms of hepatitis B vaccine are sufficient in infants to obtain a high immunogenic effect.

Child, Preschool↗
PubMed1984

Hepatitis B virus serological markers in Africans with liver cirrhosis and hepatocellular carcinoma.

Serum samples were collected at the time of hospitalization from 221 black Africans suffering from cirrhosis and 453 suffering from hepatocellular carcinoma (HCC). These patients came from Senegal, Burundi and Mali, and 6655 adults from different population groups in these countries were used as controls. Hepatitis B virus (HBV) serum markers, including hepatitis B surface antigen (HBsAg), anti-HBs, antibody to hepatitis B core antigen (anti-HBc), HBeAg and anti-HBe, were determined by radioimmunoassay, while alpha-fetoprotein and complexes between HBsAg and IgM were detected by ELISA tests. HBsAg was detected in 11.8-17.6% of controls as opposed to 63.3% of patients suffering from cirrhosis and 62.7% of patients suffering from HCC. There was less evidence for HBV replication in cirrhosis and HCC in older patients. A significant increase in the frequency of HBsAg/IgM complexes was found in passing from the HBsAg chronic carrier state (13.9%) to cirrhosis (29.9%) and finally to HCC (33.7%).

Adolescent↗
PubMed1984

Immune response to hepatitis B vaccine in infants and newborns: control trial in an endemic area (Senegal).

In 1978 it was suggested that hepatitis B (HB) vaccine should be used to prevent the early hepatitis B surface antigen (HBsAg) carrier state in children. Immunization was effected by 3 injections of HB vaccine at one-month intervals followed by a booster injection after one year. Children in a control group were immunized with DT-polio vaccine according to the same schedule. The anti-HBs response of the children to HB vaccination was studied in relation to their hepatitis B virus (HBV) serum markers prior to immunization. Of the seronegative children, 70.5% responded to immunization after 2 injections of 5- g doses of HB vaccine and 94% after the third injection. The efficacy of the vaccine was demonstrated by comparison of HB events after one year in 309 seronegative children immunized with HB vaccine and 252 seronegative children immunized with DT-polio vaccine, and after two years in 101 and 119 children, respectively. The incidence of the HBsAg carrier state was reduced by 80% in susceptible children. In order to eliminate the perinatal transmission occurring in newborns with HBsAg-positive mothers, a study of immunization at birth has been instituted. A total of 86 newborns responded to the vaccination as well as older children, irrespective of the HBV status of their mothers. After one year, the incidence of the HBsAg carrier state was reduced by 80%. In Africa, immunization teams have a limited amount of time to devote to each rural community. The immunogenic effect of 2 doses of HB vaccine given at an interval of 2 or 6 months has therefore been investigated. All were given a booster dose one year after the first injection of vaccine. No difference was observed in the seroconversion rate or in the anti-HBs titres as between the two protocols. These results demonstrate that 2 doses of 5 micrograms of HB vaccine are sufficient to obtain a high immunogenic effect in infants. In addition, an investigation was carried out on the immune response to HBsAg and tetanus toxoid antigen when administered simultaneously to children as HB vaccine and DT-polio vaccine. The immune response was at least equal to that observed after administration of these vaccines separately.

Child, Preschool↗
PubMed1983

Lack of anti-HBc IgM in neonates with HBsAg carrier mothers argues against transplacental transmission of hepatitis B virus infection.

Transplacental transmission of hepatitis B virus infection was studied in 51 Senegalese neonates born to mothers who were chronic carriers of HBsAg. 13 mothers were positive for both HBsAg and HBeAg. Mother-to-infant transmission of these two markers was different with 3 children being HBsAg positive and HBeAg negative at birth and 6 being HBsAg negative but HBeAg positive. At birth none of the 51 children had anti-HBc IgM detected by a highly specific enzyme immunoassay, indicating that none had had a primary immune response in utero to HBV infection. These HBV serum markers in newborn infants indicate contamination by maternal blood at delivery rather than active infection in utero. Prophylaxis at birth is advisable in children of mothers who are chronic carriers.

Adolescent↗
PubMed1983

Hepatitis B vaccine: further studies in children with previously acquired hepatitis B surface antigenemia.

Three doses of inactivated hepatitis B vaccine were given at 1-month intervals to 31 hepatitis B surface antigen (HBsAg)-positive Senegalese children aged between 3 and 24 months. A control group of 18 HBsAg-positive Senegalese children received diphtheria-tetanus-polio vaccine. Immunization of HBsAg-positive infants with hepatitis B vaccine was safe but inefficient. After a 12-month follow-up, the prevalence of HBsAg chronic carriers was not significantly reduced in the hepatitis B vaccine group as compared with the control group: 48.4 and 66.7%, respectively. The presence of hepatitis B antigen was found to be a major risk factor for HBsAg-positive children to develop a chronic carrier state. The risk of developing an HBsAg chronic carrier state was also related to advancing age at time of enrollment in the study.

Carrier State↗