Effectiveness of a mass immunization campaign against serogroup C meningococci in children in the Federal State of Santa Catarina, Brazil

Abstract

In addition to vaccine efficacy studies, there is a pressing need to evaluate vaccine effectiveness in a way that takes into account the limitations of health care systems in certain settings. An attempt to reach this objective was exemplified by a vaccination campaign against serogroup C meningococci in the federal state of Santa Catarina, in Brazil. A polysaccharide vaccine against serogroup C meningococci was administered to all individuals between 6 months and 14 years of age in March, 1996, in the municipalities that had the highest incidence of meningococcal disease in the previous year. All cases of the disease due to this serogroup observed in Santa Catarina during a 1-year period before and after the vaccination were included in the analysis. The cumulative incidence rate ratio was calculated for the unvaccinated compared to the vaccinated area. As a second step, the ratio of this quantity for the period before and after the vaccination, i.e. the ratio of the rate ratios (RRR), was calculated. One minus RRR was used to estimate the vaccine effectiveness. In the general population, the vaccine effectiveness was 74.3% (95% confidence intervals 52.7% to 99.6%). In children 6 months to 14 years, vaccine effectiveness was 93.1% (85.2% to 100%). Vaccine effectiveness could not be confirmed within more specific age bands, probably due to the lack of statistical power. It is concluded that group C meningococcal vaccine is effective in reducing the occurrence of meningococcal disease in children 6 months to 14 years of age, and that the ratio of rate ratios (RRR) in a useful method to evaluate vaccine effectiveness.

Phenotypic characterization of Neisseria meningitidis strains isolated from invasive disease in Brazil from 1990 to 2001

“…However, there was an increase in MenC isolation in those aged ¡5 years in the south and southeastern states of São Paulo and Rio de Janeiro (1994)(1995)(1996), as well as in those 15-24 years old, mainly from Rio de Janeiro (1995). These increases and the age shift to adolescents reflect MenC outbreaks reported in those geographic regions during the 1990s (Barroso et al, 1996;Kupek et al, 2001;Sacchi et al, 1994Sacchi et al, , 1995.…”

Incidence, epidemiology and etiology of acute meningitis in Mures County – an observational study

“…In countries where the anti-meningococcal vaccine is already implemented, we can observe a tendency to concentrate the cases in the 1 -4 years old age group, but especially under 2 years old, an age when the vaccine is not effective [19,20].…”

Estimating potential demand and supply of dengue vaccine in Brazil

“…The reported coverage levels for mass vaccination among both children and adults with various antigens (influenza, meningococcal C vaccine, Yellow Fever) in Brazil are also high (70-95%), and we used those coverage levels to estimate the coverage for dengue vaccination. [15][16][17] Achieving high coverage with a 2 or 3-dose regimen and including older age-groups in the target population in mass vaccination pose challenges. Therefore, we assumed different mass vaccination coverage for different age cohorts.…”