Related Experiment Videos
Measles incidence, vaccine efficacy, and mortality in two urban African areas with high vaccination coverage
P Aaby1, K Knudsen, T G Jensen
1Institute of Anthropology, University of Copenhagen, Denmark.
Insights
Measles vaccination before 9 months is crucial in urban Africa. Early vaccination significantly reduces measles incidence and mortality, improving disease control in hyperendemic areas.
Area of Science:
- Epidemiology
- Vaccinology
- Public Health
Background:
- Measles remains a significant public health concern in hyperendemic urban African settings.
- Vaccine coverage varies, impacting disease incidence and mortality rates.
Purpose of the Study:
- To prospectively examine measles incidence, vaccine efficacy, and mortality in two districts with differing vaccination coverage.
- To assess the impact of vaccination timing on measles outcomes.
Main Methods:
- Prospective cohort study in two districts (Bandim 1: 81% coverage, Bandim 2: 61% coverage) in Bissau.
- Analysis of measles incidence, vaccine efficacy, and mortality hazard ratios.
- Adjustment for vaccination status and age at vaccination.
Main Results:
- Higher measles incidence observed in the lower-coverage district (Bandim 2) between 9 months and 2 years (13.7% vs. 6.1%).
- Vaccine efficacy was estimated at 68%, unrelated to age at vaccination.
- Measles vaccination demonstrated a 66% protective efficacy against mortality (hazard ratio 3.0 for unvaccinated).
Conclusions:
- Vaccinating before 9 months is essential for measles control in hyperendemic urban African areas.
- Current vaccination strategies may need adjustment to improve efficacy and reduce disease burden.
- Measles vaccination significantly reduces mortality, highlighting its public health importance.
Abstract:
Measles incidence, vaccine efficacy, and mortality were examined prospectively in two districts in Bissau where vaccine coverage for children aged 12-23 months was 81% (Bandim 1) and 61% (Bandim 2). There was little difference in cumulative measles incidence before 9 months of age (6.1% and 7.6%, respectively). Between 9 months and 2 years of age, however, 6.1% contracted measles in Bandim 1 and 13.7% in Bandim 2. Even adjusting for vaccination status, incidence was significantly higher in Bandim 2 (relative risk 1.6, P = .04). Even though 95% of the children had measles antibodies after vaccination, vaccine efficacy was not more than 68% (95% confidence interval [CI] 39%-84%) and was unrelated to age at vaccination. Unvaccinated children had a mortality hazard ratio of 3.0 compared with vaccinated children (P = .002), indicating a protective efficacy against death of 66% (CI 32%-83%) of measles vaccination. These data suggest that it will be necessary to vaccinate before age 9 months to control measles in hyperendemic urban African areas.