Primary health care is defined as essential health care made accessible at a cost the country and community can afford, with methods that are practical, scientifically sound and socially acceptable. Accessibility of health services, going beyond just physical access, and including economic, social and cultural accessibility and acceptability, is of fundamental significance to reflect on health system progress, equity and sustainable development. Good management of immunization programmes is essential to the reduction of morbidity and mortality from major childhood infectious diseases, and is integral to the achievement of sustainable development. It is usually calculated for women married or in union of reproductive age, but sometimes for other base population, such as all women of reproductive age at risk of pregnancy.