Saowani Chumdermpadetsuk

Long term hepatitis B vaccine in infants born to hepatitis B e antigen positive mothers

Neonates of hepatitis B surface antigen (HBsAg) positive and hepatitis B encoded antigen (HBeAg) positive mothers received 10 μg of recombinant hepatitis B vaccine at months 0, 1, 6, or 0, 1, 2, 12, with or without immunoglobulin at birth, and were followed up to the age of 8 years for HBsAg, anti-HBc, and anti-HBs. Some were boosted at month 60. The overall vaccine protection at month 12 was 96.2%. No child became a chronic carrier beyond the age of 3 years, showing that this vaccine provides immediate protection against HBsAg carriage, and long term protection against fetally acquired HBsAg. After month 60 hepatitis B serological markers without disease, indicating re-exposure to HBV, reappeared in comparable numbers among boosted and non-boosted children (5 for a total of 167 children).  This vaccine provides long term protection against hepatitis B chronic carriage and infection in high risk neonates with or without a month 60 booster. A booster at the age of 5-6 years or 11–12 years would reduce HBV infection, viral circulation and transmission, while ensuring long term antibody persistence.

Comparison of a recombinant DNA hepatitis B vaccine alone or in combination with hepatitis B immune globulin for the prevention of perinatal acquisition of hepatitis B carriage

The protective efficacy of a recombinant DNA yeast-derived hepatitis B vaccine was assessed alone or in combination with hepatitis B immune globulin (HBIg) in neonates born to surface antigen (HBsAg)-positive and e antigen (HBeAg)-positive mothers. Neonates received either a 10 micrograms dose of vaccine alone or the same dose of vaccine plus 0.5 ml HBIg within 12 h of birth. All infants subsequently received 10 micrograms of vaccine at 1, 2 and 12 months. Only two of the 58 (3.4%) newborns of HBsAg-positive/HBeAg-positive mothers receiving vaccine alone became chronically infected with hepatitis B virus (HBV) while all infants administered vaccine + HBIg were protected. These results indicate that although the administration of HBIg can increase the protection rate, the use of vaccine without concomitant administration of HBIg according to the above schedule could considerably reduce the risk of perinatal HBV transmission.

Safety, immunogenicity, and kinetics of the immune response to a single dose of virosome-formulated hepatitis A vaccine in Thais.

The safety and immunogenicity of a single dose of virosome-formulated hepatitis A vaccine was evaluated in healthy seronegative Thai volunteers. Immunization elicited primarily mild transient reactions which did not interfere with normal activities. All subjects possessed > 20 mIU of anti-hepatitis A virus antibody per ml of serum one month after immunization. Such a prolonged rise in antibody titre is characteristic of virosome-formulated vaccines. Protective titres (> 20 mIU ml-1) were maintained by all subjects over the one-year observation period.

Prevalence of hepatitis E virus infection in Thailand.

Hepatitis E, also known as epidemic, non-A, non-B hepatitis, is an acute, enteric, infectious disease. The disease is usually mild, except in pregnant women, who suffer a high fatality rate from fulminant hepatic failure. Information on the disease in Thailand is limited. The prevalence of antibodies to the aetiological agent, hepatitis E virus (HEV), was therefore studied, in various groups of subjects from several regions of this country, using commercial ELISA for anti-HEV IgG and IgM. The prevalence of anti-HEV IgG, which was 9%-22% in the adult subjects (blood donors, pregnant women, patients with acute hepatitis and cases seen during an outbreak of hepatitis), increased with age. It was relatively low in children and adolescents from Bangkok (3.6%) and in children from the north-east (1.8%-6.2%) and south (2.3%) of the country. Five (7%) of the 68 patients with acute viral hepatitis who were tested for anti-HEV IgM were found positive. Although these five cases had jaundice (four cases), diarrhoea (three) and/or dark urine (at least four cases), all of these clinical signs were self-limiting and had no sequelae. Given the apparently high prevalence of HEV infection in young adults in Thailand, control measures, including provision of clean water supplies and better personal sanitation and food hygiene, should be implemented to prevent an epidemic of the disease.

The Immunogenicity and Reactogenicity of Combined Tetravalent Diphtheria, Tetanus, Pertussis, and Hepatitis B Vaccine in Infants

The World Health Organization recommends that countries with hepatitis B (HB) virus carrier rates of 2% or greater integrate HB vaccination into their immunization programs. The combination of HB vaccine with diphtheria, tetanus, and pertussis (DTP) would greatly simplify this integration process. Two lots of a combined DTP-HB vaccine were evaluated with a local DTP vaccine used as a control. Vaccinations were administered at 2, 4, and 6 months of age to 160 infants. Antibody titers were measured in blood samples obtained just before vaccination and 4 weeks after the third dose. Reactions to vaccinations were subjectively evaluated by the infants’ parent or guardian. No serious adverse events were reported in this trial. One month after dose 3, all infants had protective levels of D and T antibody titers and satisfactory levels of Bordetella pertussis antibody. Over 98% of infants receiving DTP-HB had protective levels of anti-HBs antibodies.

Long-term antibody persistence after booster vaccination with combined tetravalent diphtheria, tetanus, whole-cell Bordetella pertussis and hepatitis B vaccine in healthy infants

Combining HB vaccine with routine paediatric vaccines has been recognized as the best means of universal vaccination against hepatitis B. Our objective was to evaluate the long-term antibody persistence of such a combined vaccine in an area of high hepatitis B endemicity. We have shown that a DTPw-HB vaccine was safe and immunogenic when given as a booster dose at 18 months of age. One month after the booster dose of DTPw-HB vaccine, at least 97.8% of subjects had seroprotective anti-HBsAg levels, and 1 year later at least 93.9% of these subjects remained seroprotected against HBsAg. Immune responses to the DTPw components were similar or greater than those of the commercial DTPw vaccine given to the control group. This DTPw-HB vaccine, which showed good long-term anti-HBsAg antibody persistence, could advantageously replace separate DTPw and HB vaccines in areas of high hepatitis B endemicity in terms of clinical, economic and strategic benefits.