Two-dose hepatitis B immunisation regimen for infants

Prevention of hepatitis B virus infection: from the past to the future

About 3-5 % of the world's population is chronically infected by hepatitis B virus (HBV) and is at risk of developing liver cirrhosis or hepatocellular carcinoma. The risk of dying prematurely because of chronic HBV infection is higher in younger people. The current strategies to prevent HBV infection involve immunization (active and/or passive) and antiviral chemoprophylaxis. The vaccines available for active immunization, containing hepatitis B surface antigen, are safe and confer long-term immunity in most healthy subjects. Since the vaccination is unsatisfactory in some patients, e.g., those with chronic kidney disease, human immunodeficiency virus infection, type I diabetes mellitus, and celiac disease, new strategies of vaccination are required. The neonatal, infant, and adolescent routine program vaccination in about 180 countries has greatly decreased the disease burden. Passive immunization with specific HBV immunoglobulins is recommended after single acute exposure, in infants born to infected mothers, and in HBV-infected patients undergoing liver transplantation combined with nucleoside/nucleotide analogues (chemoprophylaxis). Chemoprophylaxis is also indicated in HBV carrier candidates for immunosuppressive treatment and in patients with occult B infection undergoing immunosuppressive therapy or hematopoietic stem cell transplantation. Since HBV is not eradicable by an immune response or by antiviral drugs developed so far, the only preventive strategy remains global neonatal vaccination in all countries, firstly in HBV-endemic countries.

Anti-HBs responses in children vaccinated with different schedules of either plasma-derived or HBV DNA recombinant vaccine

This study evaluated the immunogenic and protective effects of plasma-derived and DNA recombinant anti-hepatitis B virus vaccines administered to infants at various ages and with different vaccination schedules: 3 monthly doses in the first 3 months of life, 3 doses (at 3, 5 and 11 months) or 2 doses (at 1 and 3 months) or 2 doses (at 3 and 5 months). Anti-HBs (hepatitis B surface) and anti-HBc (hepatitis B core) markers were investigated twice: one month and ten years after vaccination in 261 children immunized with plasma-derived vaccine, and one month and five years after vaccination in 449 children immunized with DNA recombinant vaccine. In all groups, the appearance of anti-HBs protective levels one month after vaccination and their persistence in the following years were found in a larger number of subjects when the vaccine doses had been administered after the third month of life rather than in the first three months. Moreover, our results show that the reappearance of surface antibodies a week after the booster, in vaccinated children who became anti-HBs- in the years following vaccination, occurred in a larger number of subjects when the primary vaccination with 3 doses had been performed in the first quarter or with 2 or 3 doses in the second quarter. In contrast, protective levels of anti-HBs were found in a small number of children belonging to the group vaccinated with 2 doses in the first three months, and among them the majority seroconverted only one month after the booster. Anti-HBc was found 10 years after vaccination in only one child immunized with 2 doses of plasma-derived vaccine, and 5 years after vaccination in two children immunized with 2 doses of DNA recombinant vaccine. All these children were found to lose anti-HBs, and none of them had signs of disease or became a carrier. Based on these results, the disappearance, in some children, of protective levels of anti-HBs in the years following vaccination does not mean the loss of anti-HBV protection. In fact, the trial showed that they reacted immediately to booster stimulation, demonstrating a solid immunologic memory. Therefore, there may be no reason for giving booster injections when the vaccination of infants is carried out correctly.

Anti-HBs levels in infants of hepatitis B carrier mothers after delayed active immunization with recombinant vaccine concomitant with DTP-polio vaccine: is there need for a second dose of HBIg? Dutch Study Group on Prevention of Neonatal Hepatitis B

The need for an additional dose of hepatitis B immune globulin (HBIg) was studied by comparing infants receiving 1 ml HBIg at birth followed by hepatitis B immunization, concomitant with DTP-polio vaccine, at 3, 4, 5 and 11 months (schedule E), with infants receiving the same schedule with additional HBIg at 3 months (schedule F). The immune response to recombinant hepatitis B vaccine (20 micrograms) was evaluated in 195 infants born to HBsAg-positive mothers allocated to groups E and F and compared with historic controls who received plasma vaccine (10 micrograms) according to schedule F. Blood samples were drawn at 0, 3, 4, 6, 11, 12 and 24 months of age. No difference in efficacy between the two schedules was observed; 8 and 6% of infants born to HBeAg-positive HBsAg carrier mothers in groups E and F, respectively, became HBsAg carriers. Passively acquired antibodies at birth remained present for about 5 months in most infants. The seroprotection rates (anti-HBs > or = 10 IU l-1) were over 90% at all time points and similar for groups E and F. The titres of anti-HBs attained during the first 6 months were statistically lower (p < or = 0.02) for group E than for group F but similar thereafter. Anti-HBs titres in infants receiving the recombinant vaccine were significantly lower than in infants receiving the plasma vaccine (p << 0.001). Supplemental doses of HBIg in infants receiving a high dose of HBIg ( > 200 IU) at birth and the first dose of vaccine at the age of 3 months are not advised.

A pilot model of vaccination against hepatitis B virus suitable for mass vaccination campaigns in hyperendemic areas

A hepatitis B vaccination campaign was carried out in a town of 60,000 inhabitants, Afragola, Campania, Italy, a hyperendemic area for hepatitis B where HBsAg prevalence was 13.4% and anti-HBc prevalence was 64.7%. This experimental pilot project aimed to reduce the incidence of both acute and asymptomatic viral hepatitis B and of related chronic liver complications. From 1983-1989, 8,400 subjects were vaccinated: 6,900 children up to 10 years of age and 1,500 subjects from 11-60 years of age. High seroconversion rates were observed: 99.0% in all children under one year of age, 96.0% in the older children, and 86.7% in adults. The rate of infection in Afragola has diminished from 63/100,000 in 1983 to 10/100,000 in 1989. Carriers of HBsAg decreased in the general population (7.3% compared to 13.4%), especially in children up to 10 years of age (1.0% compared to 9.0%). In babies who received hepatitis B vaccine at the same time as compulsory vaccinations compliance was 98% while it was 80% in babies who were vaccinated separately. In June 1991 the Italian Parliament promulgated a decree which imposes hepatitis B vaccination for all newborn babies at 3, 5, and 11 months of age, at the same times as the mandatory childhood vaccinations (diphtheria, tetanus, and polio) according to a new protocol (Piazza scheme) which has been in use since January 1987 in our pilot vaccination campaign in Afragola.

Immunogenicity of hepatitis B vaccine (HEVAC B) in children with advanced renal failure

The immune response after hepatitis B (HB) vaccine HEVAC B was studied in 33 children (mean age 10 +/- 4 years) with advanced renal failure. Responders and protected patients were defined by antibody titres to HB surface antigen (anti-HBs) of greater than 10 and 50 mIU/ml, respectively. All received the initial recommended three injections at monthly intervals, and 23 received a booster injection (IB) 11 +/- 1 months after the third injection (I3). Loss of protection after I3 led to additional injections in 8 patients (25%). Vaccine was well tolerated and no HB infection occurred during the follow-up period (19 +/- 10 months). The percentage of responders was 91% 2 +/- 1 months after I3, and 100% 1 month, 13 +/- 1 months and 26 +/- 2 months after IB. The percentages of protected patients at these dates were 91%, 95%, 100% and 100%. Anti-HBs titres 1-3 months after I3 were useful for indicating those patients likely to have a rapid decline in anti-HBs titres, thus requiring serial anti-HBs determinations and additional injections to prevent a loss of protection. We conclude that at the expense of a reinforced vaccination schedule in 25% of patients, HEV AC B vaccine can safely achieve a sustained protection in more than 90% of uraemic children.

Immunogenicity of low doses of hepatitis B vaccine in children: a study in 650 New Zealand children

Six hundred and fifty New Zealand children from 2-12 years of age were vaccinated three times with 2 mcg intramuscular (IM) doses of Merck Sharp and Dohme plasma-derived hepatitis B vaccine (H-B-Vax), at 0, 1, and 6 months, and tested 2-3 months later for antibody to hepatitis B surface antigen (anti-HBs) by radioimmunoassay (RIA). Overall, 96.5% of the children seroconverted for anti-HBs by RIA, having levels greater than 2.1 RIA S/N units, with 91.2% having values greater than 10 S/N units. Anti-HBs levels were also determined by enzyme immunoassay (EIA), by which method a significantly better response was demonstrated in 2-4-year-olds than in older children. This study demonstrated that a satisfactory anti-HBs response was obtained using one-fifth of the recommended doses of hepatitis B vaccine.