Pneumonia is the leading infectious cause of death in the world and was responsible for an estimated 2.6 million deaths in 2017, according to the Global Burden of Disease (GBD). Three-quarters of these deaths are among two vulnerable populations – 800,000 are among children under five years of age and 1.1 million are among adults over 70 years of age. This means that every country is dealing with a pneumonia burden. In high income countries, pneumonia deaths concentrate among the elderly, in low income countries it is children who bear the greatest burden and in many middle income countries there is a “double-burden” of pneumonia among both children and the elderly.
This burden would be much higher without the vaccines that have been developed to prevent some of the leading causes of pneumonia; principally the pneumococcal conjugate vaccine (PCV) and the haemophilus influenzae type B vaccine (Hib), which target the leading bacterial causes of childhood pneumonia. Vaccines against diphtheria, tetanus and pertussis (DTP) and measles (MCV) are also critical pneumonia-fighting vaccines, as pertussis and measles can also cause pneumonia.
The expansion of this “basket” of pneumonia-fighting vaccines has contributed to the dramatic fall in childhood pneumonia deaths in recent decades, from an estimated 1.7 million in 2000 to 800,000 in 2017. For example, after Kenya introduced the PCV in 2011, the average annual incidence of severe pneumococcal disease dropped by 92% among children under five years of age, and hospital admissions fell sharply. Studies also suggest that childhood PCV vaccination leads to substantial protection across the whole population within a decade. Although there are no routine estimates of pneumonia deaths prevented among the elderly with PCV vaccination among children, some countries now recommend routine pneumococcal vaccination for those aged over 65 years.
The pneumonia-fighting vaccines could have an even greater impact if all children received them and if the elderly were protected in every country. This is particularly true for the PCV, which only reaches 47% of children in the world, leaving the majority unprotected. PCV coverage rates vary widely across World Health Organization (WHO) regions, from 13% and 17% in the Western Pacific and South East Asian regions to 78% and 82% in Europe and the Americas respectively. The Eastern Mediterranean region has a rate of 53% and Africa records an impressive 73%, a testament to the partnership between Gavi, the Vaccine Alliance (Gavi) and African governments and the support of the Advanced Market Commitment (AMC), an innovative financing mechanism that has underwritten PCV expansion in most Gavi-eligible countries and prevented an estimated 700,000 deaths. But major gaps remain, especially in a subset of Gavi-eligible countries and those that are not eligible for Gavi support.
For example there are 54 countries that have not yet introduced the PCV with 146 million children under five living in them. These “zero-dose PCV”* countries are in every region of the world. The Western Pacific is home to 96 million children under five, followed by the Eastern Mediterranean with 24 million, and Africa with 10 million. Europe is home to seven million, Southeast Asia to six million and the Americas to three million children. All of these children are vulnerable to infection with pneumococcal disease.
The cost of this exposure is ultimately measured in children’s lives lost due to pneumonia – an estimated 83,000 every year in the zero-dose PCV countries – representing 10% of all pneumonia deaths among children under five. The zero-dose PCV countries with the heaviest burdens of child pneumonia deaths include China, Chad, Egypt, South Sudan, Somalia, Guinea, Tajikistan, Viet Nam, North Korea and Iran. Together these ten countries account for more than 90% of the 83,000 child pneumonia deaths occurring in zero-dose PCV countries.
*Note Gavi refers to “zero-dose children” as those who do not receive the DTP vaccine. This report refers to “zero-dose PCV children” as those who do not receive the PCV vaccine.
In addition to the zero-dose countries, of great concern are the countries with PCV coverage rates between 1% and 59%. There are even more children living in these low-dose PCV countries – 195 million. They include India with 117 million children under five years of age and 6% PCV coverage, Nigeria with 34 million children and 57% PCV coverage, Indonesia with 24 million children and 8% PCV coverage, the Philippines with 11 million children and 43% PCV coverage, Iraq with 5.4 million children and 32% PCV coverage, Haiti with 1. 3 million children and 1% PCV coverage, Papua New Guinea with 1.1 million children and 43% PCV coverage, Lao PDR with 800,000 children and 56% PCV coverage and the Central African Republic with 740,000 children and 47% PCV coverage. Together, these countries account for 374,000 child pneumonia deaths, almost half (49%) of the global total.
Together, zero and low-dose PCV countries are home to 340 million children under five; almost half of all children under five in the world. These children are dangerously exposed to pneumonia, and so are the adults around them. As many of these countries are also experiencing heavy burdens of pneumonia deaths among their elderly populations, and some among working age adults, protecting children with the PCV should also have a significant impact on reducing infections and deaths from pneumonia among the adults.
Although average global vaccine coverage rates are higher for DTP (86%), Hib (72%) and measles (69%) vaccines, they are much lower in many of the high-burden pneumonia countries, including those with zero or low-dose PCV coverage. For example, DTP and Hib coverage are below 60% in Nigeria (57%), Chad (41%), South Sudan (49%), Somalia (42%), Guinea (45%) and the Central African Republic (47%).
In addition, very few high-burden pneumonia countries have achieved high coverage of two doses of the measles vaccine. Among the countries with more than 1,000 child pneumonia deaths, only 19 have measles vaccine coverage above 80%. This underscores the urgency of increasing and sustaining high coverage of the measles vaccine. The decline of measles deaths is one of the greatest public health achievements. Between 1990 and 2017, measles deaths among children fell from an estimated 700,000 to 95,000, according to the GBD, largely as a result of high and sustained measles vaccine coverage. Recent outbreaks of measles, due to falls in coverage in some countries, reveal how critical it is to maintain universal coverage of the measles vaccine.
To summarize, one out of every two children under five in the world is not fully protected with the pneumonia-fighting vaccines. These children are dangerously exposed to pneumonia and at risk of infecting others. Of greatest concern are the high-burden pneumonia countries with zero or low doses of the PCV, less than 60% coverage of three doses of the DTP and Hib vaccines and two doses of the measles vaccine. All of these countries are Gavi-eligible and include Nigeria, Chad, Somalia, South Sudan, Guinea and the Central African Republic. Also of concern are a second cluster of six countries with very low coverage of all four vaccines. Four of these countries are Gavi-eligible – Afghanistan, Haiti, Lao PDR and Papua New Guinea – while two are not – Angola and the Philippines.