The authors analyzed 974 healthy unvaccinated children in Cuba, and found that by the age of 4-5 years, 99.7% of them had natural Hib immunity. Natural Hib immunity was also found in Finland (79%) and in India (80%).
Therefore, the WHO recommends introducing this vaccine into the national immunization schedule only in countries that can afford it financially, without taking resources from other important vaccines.
Natural immunity to Hia was found in indigenous in Canada. More: .