However, cases of meningococcal serogroup C disease continued to occur among persons who were eligible for vaccination, prompting an investigation of vaccine effectiveness. The results of this study identified no confirmed cases of meningococcal serogroup C disease in vaccinated or partially vaccinated individuals through December 2011, consistent with the high effectiveness of

MenC conjugate vaccines observed in the United Kingdom, Quebec, Spain and other settings [10], [15], [16] and [17]. Reasons for non-vaccination see more among case patients who were eligible to receive MenC vaccine need to be investigated to inform future vaccination strategies. Offering MenC vaccine over an extended period of time might have helped achieve coverage targets; national vaccination campaigns against influenza A(H1N1) and rubella in Brazil achieved coverage targets among persons 20–29 years old by providing multiple opportunities for vaccination

over an extended period [18] and [19]. The increase in serogroup C meningococcal disease in Salvador, Brazil, was characterized by elevated attack rates among adolescents and young adults, as well as young children, ABT 888 with high case-fatality, similar to patterns of epidemic meningococcal disease described in other settings [10], [15] and [16]. Data from surveillance for meningococcal disease, especially the availability of population-based data to compare disease incidence by age group in the city of Salvador [7], helped prioritize limited vaccine supplies. The increase of meningococcal serogroup C disease in Salvador followed a shift from predominance of

serogroup B to serogroup C first described in São Paulo in southeast Brazil [3], and spreading throughout the country [4]. While the emergence of a virulent serogroup C clone belonging to sequence type 103 complex may have contributed to epidemics in Brazil, steadily increasing incidence of serogroup C meningococcal disease has been reported from the greater São GPX6 Paulo metropolitan area since the late 1980s [3]. Further, meningococcal epidemics may occur due to a variety of factors; shifts of predominant serogroup have been identified in other settings in Brazil without occurrence of epidemics [20]. For example, serogroup C meningococci belonging to the sequence type 103 complex have been identified in Salvador since 1996 (J. Reis, unpublished data). This clone has been associated with epidemics of meningococcal disease in Europe and other regions since 2000 [3] and [21]. Natural cycles in meningococcal disease complicate efforts to document short-term impact of vaccination. Continuous surveillance in Brazil for meningococcal disease and strain characterization is needed to establish a baseline for vaccine impact assessments. This study is subject to a number of limitations.