Globally, coverage of the third dose of DTP is 15% higher among children in the highest compared to lowest wealth quintile. However, this masks differences of up to 64% in the most inequitable countries (Nigeria).
Pertussis
Vaccinated children are far less likely to experience stunting compared to unimmunized children
A study in Kenya revealed that immunization with polio, BCG, DPT and measles had protective effects with respect to stunting in children under 5 years of age. In children under the age of 2 years, immunized children were 27% less likely to experience stunting when compared to unimmunized children. Additionally, children who suffered from cough or diarrhea in the 2 weeks prior to the study showed an 80-90% higher probability of being underweight or experiencing wasting.
Vaccination linked to higher IQ and language scores
Vaccination of children in the Philippines against 6 diseases was found to significantly increase IQ and language scores (compared to children receiving no vaccinations) and was estimated to have a 21% rate of return.
Vaccinated children performed better on several cognitive tests
In a study of immunization in the Philippines, children vaccinated against 6 diseases performed significantly better on verbal reasoning, math, and language tests than those who were unvaccinated. (note: Researchers did not find an association with physical growth.)