Administration Of Booster Dose Research Articles

Immunization in children with HIV seropositivity at birth

To evaluate the humoral response to routine childhood immunization of HIV-infected children. Response rate, antibody titres and persistence after polio and tetanus vaccination were compared in 72 children with HIV seropositivity at birth and divided according to HIV infection status as determined by clinical and laboratory tests. Polio antibodies were titred in a microneutralization test (positive titres, > or = 1:4), and antibody to tetanus toxoid with a passive haemagglutination method (protective titres, > or = 1:1024). The response rates to polio and tetanus vaccination (> 80 and > 75%) were similar in the HIV-infected and non-infected children, as were antibody levels. In the subgroup with sera obtained some months after the last dose of vaccine, polio antibody levels decreased in all four HIV-infected and in three of the seven non-infected children; protective tetanus antitoxin levels were detected in three of the six infected and in all three non-infected children. This study demonstrates the ability of children with HIV infection to respond adequately to the two vaccines considered, although tetanus antitoxin levels were inferior, compared with those in the seroreverted children. The unsatisfactory antibody levels observed in the admittedly few HIV-positive children studied some months after the last vaccination could be the result of a lower initial protective level and not necessarily an expression of severely impaired immunocompetence. The administration of booster doses in addition to the traditional immunization schedule could be useful in children with HIV infection.

Prevalence of hyperimmunization against tetanus in a national sample of 18–26 year old immune subjects in Italy

Prevalence of tetanus hyperimmunization was estimated among 3217 immune subjects to be approximately equal to 11%. Hyperimmunization was associated with age, area of residence and health care availability. Indiscriminate administration of booster doses of tetanus vaccine could result in some areas in unnecessary revaccinations and possibly hypersensitivity reactions. The immunization policy regarding booster doses should be based on factual evidence and not on rigid recommendations.

Hepatitis B vaccine in infants from an endemic area: long-term anti-HBs persistence and revaccination.

Persistence of anti-HBs in 156 Senegalese infants immunized with hepatitis B vaccine was studied for periods ranging from 2 to 6 years after booster dose administration. Six years after the booster dose, 90.4% of the infants had detectable anti-HBs antibodies, with 78.1% having titers higher than 10 mIU/ml. The geometric mean titer was 60 mIU/ml. Females showed higher anti-HBs values than males. In a group of 11 infants who received no booster dose, anti-HBs antibodies were detectable 7 years after the first dose. However, the geometric mean titer was lower (26 mIU/ml). Revaccination (56 infants) led to an increase of the geometric mean titer to 469 mIU/ml 2 months later. These results show that a booster injection every 5-6 years should provide adequate protective anti-HBs levels in infants.

Comparative Studies on Tree Pollen Allergens

The major allergen of birch pollen, BV45, was isolated and conjugated to 2-<i>o</i>-methoxy polyethylene glycol-4,6-dichloro-5-triazine (mPEG). The molecular-weight variant of 6,000 daltons of the activated mPEG was used in an antigen-specific regulation of IgE response. In these studies 200 genetically high IgE responders (CBA/Ca) female mice were intradermally immunized by the purified BV45, with the use of various adjuvants. Four different sets of experiments were made. In the first experiment 50 mice were immunized on days 1 and 15 with BV45. This was followed by another booster dose of the native BV45 or the modified mPEG-BV45 in Freund’s incomplete adjuvants (FIA) on day 72. In the 2nd experiment, a similar procedure was performed except that booster doses were injected on day 135. Subsequently on day 136, BV45/FIA was intradermally injected. In the 3rd and 4th sets of experiments, 2 groups of 50 mice were daily immunized by intraperitoneal injections of 10 successive doses of BV45. On day 33 a dose of BV45 or mPEG-BV45 respectively, was intraperitoneally injected in each mouse. This injection was followed by other 10 successive doses of BV45. In experiment 3 no adjuvants were used, and in experiment 4 aluminium hydroxide gel was used as adjuvant. The mice immune response was assessed by analyses of the serum IgG and IgE levels. In all experiments higher IgG concentrations were shown for the immunized mice as compared to the non-treated control animals. Administration of booster doses of BV45 or mPEG-BV45 induced increases in the IgG levels. As shown in experiments 3 and 4, the mPEG-BV45-treated animals gave higher IgG responses than those treated with native allergens. Although the results of the experiments did not show a prominent decrease of IgE, we do not exclude the possibility that modified birch pollen allergens could be superior in hyposensitization therapy. The results obtained suggested within certain limitations that modified birch pollen allergens gave better results in modulating the IgG and IgE synthesis in mice as compared to the non-modified allergens. These observations are partially in agreement with papers earlier published on mPEG-modified allergens from honey bee venom, grass pollen and various tree pollens by other authors.

BOOSTER IMMUNISATION FOR DIPHTHERIA AND TETANUS: NO EVIDENCE OF NEED IN ADULTS

Recommendations to give adults diphtheria and tetanus toxoid every ten years have been based on serological surveys that have shown lower antibody levels in older populations. The purpose of an immunisation programme, however, is to prevent disease and not merely to produce antibodies. In Canada, although an immunisation programme against diphtheria has been in operation for nearly sixty years, age-specific morbidity and mortality rates for diphtheria do not show an increase with age. Similarly, age-specific death rates from tetanus do not show any increase. From Canadian surveillance data, there is no evidence to suggest that people are leaving the immune pool and entering the susceptible pool. Immunisation programmes do not need to include routine administration of booster doses of diphtheria and tetanus toxoids to adults since the benefits of the procedure do not justify the risks or costs. Continuing case-surveillance will bring to light any increase in incidence of disease justifying a need for an adult programme.