Meningococcal and pneumococcal disease

Abstract

The licensure of new vaccines in 2001 in Canada means that pneumococcal and group C meningococcal infections can be added to the list of vaccine-preventable diseases. The successful control of these two diseases will require all provincial and territorial governments in Canada to add the new vaccines to their routine immunization programs. Streptococcus pneumoniae is the most common cause of bacterial infections in children. During the past 50 years, approximately 500,000 cases of pneumococcal disease and 200 to 400 cases of meningococcal disease have occurred annually in Canada. Although all age groups are affected, the peak for both bacteria incidence is in infants younger than two years of age. The new vaccines consist of either seven pneumococcal polysaccharides or the group C meningococcal polysaccharide covalently bound to a carrier protein. Both vaccines are very safe. Local reactions occur in 10% to 20% of recipients, but are mild and last only one to two days. Fever, irritability and other general adverse events are not increased in frequency or severity by giving either of these conjugate vaccines at the same time as diphtheria-tetanus-acellular pertussis or diphtheria-tetanus-acellular pertussis-inactivated-Haemophilus influenzae type b vaccine. The pneumococcal and meningococcal conjugate vaccines are highly immunogenic at all ages, including infancy. More importantly, the vaccines also induce immune memory so that protection is expected to last many years, if not for life. The pneumococcal conjugate vaccine is 97% effective in preventing bacteremia and meningitis. The meningococcal conjugate vaccine is also very effective. Within nine months of starting routine vaccination in England and Wales, the frequency of group C disease decreased by 97% in vaccinated adolescents and by 92% in infants and toddlers. The lack of an effective vaccine against group B meningococci is an important defect in the control of meningococcal disease. When an effective vaccine is developed against group B strains, bacterial meningitis in children may join diphtheria, tetanus, H influenzae type b and polio as diseases of the past.