Associated or combined vaccination of Brazilian infants with a conjugate Haemophilus influenzae type b (Hib) vaccine, a diphtheria-tetanus-whole-cell pertussis vaccine and IPV or OPV elicits protective levels of antibodies against Hib.

This study investigated the immunogenicity and safety of including a Haemophilus influenzae type b vaccine (polyribosylribitol phosphate conjugated to tetanus toxoid, PRP-T) in three different vaccination schemes: (1) PRP-T reconstituted with a combined diphtheria-tetanus-pertussis-inactivated poliovirus vaccine (DTP-IPV//PRP-T); (2) PRP-T reconstituted with DTP and administered concomitantly with an oral poliovirus vaccine (DTP//PRP-T+OPV); and (3) PRP-T administered concomitantly with DTP at a different injection site and OPV (DTP+PRP-T+OPV). Vaccines were given at 2, 4, and 6 months of age. A total of 252 infants were enrolled, and randomly assigned to one of the three vaccination groups (84 infants in each group); 241 infants were followed until the end of the study. Antibody production against PRP, diphtheria, tetanus and pertussis antigens was satisfactory for each vaccination scheme used. A good response to Hib vaccine was elicited in each group, and 3 months after the third vaccine dose, at least 97% of children in each group had levels of PRP antibody considered to be seroprotective (>0.15 microg/ml), and over 90% of children in each group had levels over 1. 0 microg/ml. The solicited local and systemic adverse events following vaccination were mild in all groups and resolved within 4 days without medical intervention. With the exception of fever, which was more common after the second dose in children who received DTP-IPV//PRP-T, local and systemic reactions did not differ between the vaccination groups. Due to the practical advantages of combined vaccines, their use in routine immunization programs in developing countries is highly desirable. Our results show that Hib conjugate vaccine can be included in routine immunization programs that include either OPV or IPV with satisfactory immunogenicity and safety profiles. This flexible approach should facilitate the inclusion of the Hib conjugate vaccine in routine immunization programs on a world-wide scale.

Decreased point prevalence of Haemophilus influenzae type b (Hib) oropharyngeal colonization by mass immunization of Brazilian children less than 5 years old with hib polyribosylribitol phosphate polysaccharide-tetanus toxoid conjugate vaccine in combination with diphtheria-tetanus toxoids-pertussis vaccine.

A protective herd effect has been described after susceptible populations of children are vaccinated with conjugate Haemophilus influenzae type b (Hib). Hib carriage was studied in children aged 6-24 months attending day care centers in two cities in southern Brazil (Curitiba and Porto Alegre). In Curitiba, routine immunization with Hib polyribosylribitol phosphate polysaccharide-tetanus toxoid conjugate vaccine (PRP-T) in combination with diphtheria-tetanus toxoids-pertussis vaccine (PRP-T/DTP) has been offered since September 1996; DTP vaccine alone is routinely given in Porto Alegre. Children in Porto Alegre (n=643) were 8 times less likely to have received adequate Hib vaccination and 4 times more likely to be Hib carriers than children in Curitiba (n=647; i.e., point prevalence of oropharyngeal colonization, 4.8% vs. 1.2%). Point prevalence of carriage with non-type b or other nontypeable Hi was similar in children of both cities. There was a vaccination effect on carriage rates in children who received a primary 3-dose series, independent of the booster dose, suggesting that a booster may be unnecessary to induce population protection.

Economic impact of providing workplace influenza vaccination. A model and case study application at a Brazilian pharma-chemical company.

OBJECTIVE: To develop and apply a model to assess the economic value of a workplace influenza programme from the perspective of the employer. DESIGN: The model calculated the avoided costs of influenza, including treatment costs, lost productivity, lost worker added value and the cost of replacing workers. Subtracted from this benefit were the costs associated with a vaccination programme, including administrative costs, the time to give the vaccine, and lost productivity due to adverse reactions. The framework of the model can be applied to any company to estimate the cost-benefit of an influenza immunisation programme. SETTING: The model developed was applied to 4030 workers in the core divisions of a Brazilian pharma-chemical company. RESULTS: The model determined a net benefit of $US121,441 [129,335 Brazilian reals ($Brz)], or $US35.45 ($Brz37.75) per vaccinated employee (1997 values). The cost-benefit ratio was 1:2.47. The calculations were subjected to a battery of 1-way and 2-way sensitivity analyses that determined that net benefit would be retained as long as the vaccine cost remained below $US45.40 ($Brz48.40) or the vaccine was at least 32.5% effective. Other alterations would retain a net benefit as well, including several combinations of incidence rate and vaccine effectiveness. CONCLUSIONS: The analysis suggests that providing an influenza vaccination programme can incur a substantial net benefit for an employer, although the size of the benefit will depend upon who normally absorbs the costs of treating influenza and compensating workers for lost work time due to illness, as well as the type of company in which the immunisation programme is applied.

Seroconversion of a trivalent measles, mumps, and rubella vaccine in children aged 9 and 15 months.

The serological response to MMR vaccine was evaluated in 109 9-month-old infants having no history of measles vaccination, and in 98 15-month-old children who had received monocomponent measles immunisation at 9 months. The combined vaccine contained Schwarz, Urabe Am9, and Wistar RA 27/3 live attenuated virus strains. Preimmunisation antibody levels were extremely low for the 9-month-old children, indicating that maternally-transmitted antibodies do not persist at this age. In the case of mumps, preimmunisation antibody levels were significantly higher in the 15-month-old than in the 9-month-old group. A difference between groups in terms of postimmunisation antibody titres was observed only for rubella, with titres being significantly higher in the older group. Seroconversion rates were high in both groups and no serious events attributable to vaccination were observed. The MMR vaccine can thus be administered to children as young as 9 months of age. Evidence for the efficacy of a two-dose schedule, i.e. at 9 and 15 months, is presented.