The growth of global immunisation

Measles is a highly infectious viral disease whose symptoms include a high fever and rash. Complications of measles can include blindness, brain swelling and pneumonia.

A very effective measles vaccine was introduced in the late 1960s and immunisation rates have soared since 1980. As a result, the number of deaths from the disease have plummeted from 2.6 million in 1980 to 156,000 last year.

The past three decades have seen a dramatic increase in measles immunisation and a rapid decline in deaths, but there is concern that global immunisation rates have levelled off in recent years.

By 2012, 84% of children globally got one dose of measles vaccine by their second birthday. Since 2009 the WHO has recommended that all children receive a second dose of the vaccine. Since measles only affects humans it should be possible to eradicate but several targets have been missed.

Haemophilus influenzae type b (Hib) is a bacterial infection which causes severe pneumonia and meningitis, especially in young children. Children need three doses of the vaccine to be fully protected – hence the map label Hib3.

Hib has been virtually eliminated in developed countries. But more than two decades after an effective vaccine was introduced, half the world’s children are still not getting all three doses.

The first Hib vaccine was licensed in 1985. While there has been a steady increase in vaccine coverage among wealthy countries, low income countries have lagged behind.

By 2000 Hib was estimated to have caused 386,000 deaths worldwide in children under five. A major health initiative has led to a dramatic increase in coverage in poorer nations - especially across Africa - but coverage in South-east Asia remains extremely poor.

DTP is a combined vaccine protecting children against diphtheria, tetanus and pertussis (whooping cough). Pertussis remains a major cause of infant death. In 2008 it caused around 195,000 fatalities. Tetanus was responsible for over half a million infant deaths in 1980, but the death rate has since declined. Diptheria is rare except in poorer nations.

The proportion of children receiving all three doses of the vaccine is used as a key indicator of global immunisation coverage. That is because it is given to infants at around two, three and four months and so can show how effective a health service is at organising immunisation.

In 1980 only richer nations were managing to protect more than half their infants with three doses of DTP vaccine but the subsequent decade saw a dramatic rise in coverage in developing nations. Currently, more than 100 million children get fully immunised against DTP every year, but another 20 million do not get the three doses necessary for full protection.

The one in five children who miss out are almost all among the poorest families from poorer nations. The one in five children who miss out mostly come from the poorest families in the poorest nations. Weak healthcare systems and difficulties reaching remote areas and storing the vaccines at the correct temperature are pressing issues in many of these countries.