Vaccine Impact: North America
Routine Vaccination in USA and Canada
Routine pneumococcal immunization programs in North America have demonstrated the 7-valent conjugate vaccine's phenomenal impact on health. Pneumococcal disease incidence was reduced both in the vaccinated children due to the vaccine’s direct effects and in unvaccinated children and adults due to herd immunity. Routine immunization was also shown to reduce health disparities by substantially improving child survival in certain vulnerable sub populations.
The US Centers for Disease Control and Prevention (CDC) reported surveillance data on invasive pneumococcal disease in the USA before and after the introduction of the 7-valent vaccine, describing the public health impact as "phenomenal" (CDC. MMWR 2005; 54(36): 893-897).
- The incidence of vaccine-type invasive pneumococcal disease (IPD) declined by 94% among children under 5; even though the coverage rate during the surveillance period was only 68%.
- Overall incidence of IPD in children under five was 77% lower in 2005 than it was prior to vaccine introduction (CDC. MMWR 2008; 57(06):144-148).
- For every case of IPD that was prevented in a vaccinated child, more than two were prevented in an unvaccinated child or adult due to indirect (or herd) immunity (CDC. MMWR 2005; 54(36): 893-897).
- Increases in non-vaccine type disease (i.e., serotype replacement) have been seen, but the increases have been small in relation to the overall decline in disease. These data show that a further reduction of IPD might be achieved be using an expanded-valency vaccine because non-vaccine type disease was caused predominately by only one serotype (19A) (CDC. MMWR 2008; 57(06):144-148).
Routine vaccination has also eliminated racial disparities in pneumococcal disease incidence. For years, African-American and Native Alaskan/American Indian children had rates of IPD several fold higher than that of white children in the USA. Vaccination has wiped out these health disparities and the incidence of disease is now a similar low rate in all groups (Flannery B et al. JAMA 2004; 291:2253-5. Hennessy TW et al. Vaccine 2005; 23:5464-73).
According to The Public Health Agency of Canada, following introduction of universal immunization of infants with 7-valent pneumococcal vaccine in 2002, a prompt and large decline in the incidence of IPD among children under 2 years of age occurred in the Calgary region. As in the US, herd immunity was seen, with an associated fall in the incidence of PCV7 serotype invasive disease among adults aged over 65 years. (Kellner et al. CMAJ 2005; 173: 1150-1151.)