Table 1

Projected reduction in measles cases and measles deaths with measles immunisation at ages 4–10 months, Machakos, Kenya 1974–1981

Expanded programme on immunisation model8Estimated number of measles deaths in a cohort of 1000 children
Column 1Column 2Column 3Column 4Column 5Column 6Column 7Column 8Column 9Column 10
Cumulative measles incidence (%)Seroconversion from MV (%)Prevented cases (%)Vaccine failures (%)Cases prior to MV (%)EPI assumption: case death 4%Adjusting vaccination status*Adjusting vaccination status and age of infectionAdjusting vaccination status, age of infection and seronegative 50% protectionAdjusting vaccination status, age of infection and seronegative 25% protection
Age 4 months0.515158503411.311.35.78.5
Age 5 months1.03535650268.68.64.36.5
Age 6 months2.8525148119.66.87.24.05.6
Age 7 months6.1726928312.44.96.14.35.2
Age 8 months9.586791568.44.46.85.86.3
Age 9 months14.49584796.44.58.17.77.9
Age 10 months18.698824147.26.111.711.511.6
  • Bold and italic mark the month of vaccination with the lowest measles mortality given the set of assumptions specified for a specific column.

  • The estimated number of measles deaths was obtained by multiplying the number of vaccine failures (column 4) and cases prior to MV (column 5) in a cohort of 1000 children by the case death rates as indicated in the following notes:

  • * Assumption: the relative case death ratio is 1/3 for vaccinated versus unvaccinated cases, that is, 4% for unvaccinated cases and 1.33% for vaccinated cases.

  • Assumption: the relative case death ratio is 1/3 for vaccinated versus unvaccinated cases. The case death ratio is twice as high for unvaccinated cases occurring in infancy. Hence, the estimated case death ratios are 8% for unvaccinated cases occurring in infancy and 1.33% for vaccinated cases.

  • Assumption: seronegative children had 50% or 25% protection against measles. Hence, the estimated case death ratios are 8% for unvaccinated cases occurring in infancy and 1.33% for vaccinated cases, but there were fewer vaccinated cases than indicated in column 4.

  • EPI; Expanded Programme on Immunization, MV, measles vaccine.