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Meningococcal disease and vaccination in North America
1Division of Infectious and Immunologic Diseases, British Columbia's Children's Hospital, British Columbia Research Institute for Children's and Women's Health, Vancouver, Canada.
Abstract:
In North America, meningococcal disease occurs at a rate of I case per 100000 population per year, producing 2725 cases notified in the US in 1998 and 155 laboratory confirmed cases in Canada in the same year. A majority of these cases occur in the winter season and in early childhood, with a case fatality rate of approximately 10%. There has been an increase in the proportion of cases due to serogroup Y meningococci over the past decade: in 1995-98 in the US, 33% of cases were due to serogroup B, 28% were due to serogroup C and 34% were due to serogroup Y; in Canada in 1995-96, 47% of cases were due to serogroup B, 40% were due to serogroup C and 10% were due to serogroup Y. Outbreaks due to serogroup C were more common in the 1990s in the US and a number of outbreaks have occurred in Canada due to organisms from the hypervirulent ET-37 complex. College freshmen in the US in dormitories were found to be at an increased risk of disease. In addition, over the past 10 years, an outbreak of serogroup B disease occurred in the Pacific North-west of the US, with a fourfold increased rate of disease in that region. The explanations for these changes in epidemiology are unknown, but probably reflect the appearance of hypervirulent clones of meningococci and/or changing levels of population immunity. Meningococcal serogroup C polysaccharide-protein conjugate vaccines have been introduced recently in the UK, seem efficacious and offer the potential to reduce the burden of disease in the US and Canada too. Because serogroups other than serogroup C are prevalent in North America, a combination polysaccharide-protein vaccine, including C, Y and possibly W135 serogroups, would be attractive for this population. Although not currently an issue in industrialized nations, inclusion of serogroup A conjugates in any future vaccine policy would be an important decision in driving global prevention of meningococcal disease. A meningococcal conjugate vaccine against serogroup C was licensed in Canada in April 2001.
Insights
Meningococcal disease in North America is increasing, particularly serogroup Y. New conjugate vaccines targeting multiple serogroups, including C, Y, and W135, show promise for reducing disease burden.
Area of Science:
- Epidemiology
- Immunology
- Vaccinology
Background:
- Meningococcal disease affects 1 in 100,000 people annually in North America, with higher incidence in winter and early childhood.
- Serogroup Y strains have increased in prevalence over the past decade in the US and Canada.
- Outbreaks have been linked to specific hypervirulent strains and increased risk in college freshmen.
Purpose of the Study:
- To analyze the changing epidemiology of meningococcal disease in North America.
- To evaluate the potential of new conjugate vaccines for disease prevention.
Main Methods:
- Analysis of reported cases and serogroup distribution in the US and Canada.
- Review of vaccine efficacy and potential impact.
Main Results:
- Serogroup Y cases rose significantly, while serogroup C outbreaks were common in the 1990s.
- Serogroup B outbreaks also occurred, notably in the Pacific Northwest.
- Serogroup C conjugate vaccines show efficacy and potential for reducing disease.
Conclusions:
- The changing epidemiology suggests hypervirulent clones and altered population immunity.
- Combination vaccines targeting serogroups C, Y, and W135 are recommended for North America.
- Inclusion of serogroup A in future vaccines is crucial for global prevention.