2.56 million people died from pneumonia in 2017. Almost a third of these deaths where children under-5. In this entry we look at the global burden of pneumonia and what can we do to reduce the number of people dying from it.
- Pneumonia is the leading cause of death in children under 5 — more than 800,000 children died due to pneumonia in 2017.
- While still too many children die today, since 1990 we’ve seen more than 3-fold reduction in child mortality rates from pneumonia globally. The mortality rates in other age groups have remained largely the same
- The highest mortality from pneumonia occurs in Sub-Saharan Africa
- Undernutrition, air pollution and smoking pose the greatest risks for developing pneumonia
- Reducing exposure to risk factors and higher coverage of pneumococcal vaccines can reduce the number of people dying from pneumonia
- Pneumococcal vaccines could be saving the lives of almost 400,000 children annually, we look at what we could do to achieve this
In the visualization here we see global deaths from pneumonia1 by age group.
The number of children dying from pneumonia has decreased substantially over the past three decades. In 1990, more than two million children died from pneumonia every year: it was the leading cause of death in children, accounting for 20% of all childhood deaths. By 2017, this number had fallen by almost two-thirds. Improvements in the major risk factors such as childhood wasting, high air pollution, and poor sanitation as well as increased availability of treatments such as pneumococcal vaccines and antibiotics have all contributed to this decline.
As the chart shows, there’s been a 3-fold reduction in child mortality due to pneumonia over the last three decades. 363 children out of every 100,000 died due to pneumonia in 1990, in 2017 that number has fallen to 119.
The mortality rates among other age groups have remained largely the same. The highest pneumonia mortality rates in 2017 were among people aged 70 and older. 261 out of 100,000 people died in this age group, that’s just 9% decrease in mortality rates over the past 3 decades in people aged 70 and above compared to 33% in children under 5.
Increasing number of people reaching the age of 70 also means that in 2017 the majority of people, 1.13 million, who died from pneumonia where in this age group.
In the map we see death rates from pneumonia expressed as the number of deaths per year per 100,000 individuals. Note that these rates have been age-standardized, which aims to correct for differences in the age structure of a population (which are different between countries and change over time). This therefore allows us to compare the likelihood that any given individual will die from diarrheal disease across countries and through time.
We can see that most deaths from pneumonia occur in Sub-Saharan Africa as well as in Southeast-Asia. In Southeast-Asia, Philippines have particularly high pneumonia mortality rates; pneumonia is the second leading cause of death in both under-5-year-old and older than 70-year-old populations in this country.
As the map shows, children are most likely to die from pneumonia across Sub-Saharan Africa and South Asia. Just 5 countries — India, Nigeria, Pakistan, the Democratic Republic of Congo, and Ethiopia – accounted for more than half of all deaths from childhood pneumonia in 2017.
In a 2018 comment in the journal Lancet, Kevin Watkins and Devi Sridhar called pneumonia “the ultimate disease of poverty”.2 There is a strong correlation between a country’s income and child mortality from pneumonia. Pneumonia is not a disease that transmits easily across borders, its transmission is generally restricted to local communities and it can be controlled if basic health measures are available. The disease is therefore most common in places where healthcare infrastructure is lacking and people are least able to afford the treatment.3
To understand how we can reduce the number of children dying from pneumonia we need to talk about both prevention and treatment.
In the chart we show the number of child deaths from pneumonia which are attributed to various risk factors.
It contributed to 53% of pneumonia deaths in 2017. Without sufficient energy intake the body cannot cope with increased energy demands required to fight off the infection. A published literature review of pneumonia in malnourished children by Mohammod Jobayer Chisti and others found that undernourished children are between two and four times more likely to be admitted to hospital due to pneumonia and up to 15 times more likely to die from it.5
Indoor and outdoor air pollution contributed to 29% and 18% of pneumonia deaths in 2017, respectively. Studies have shown that high indoor air pollution in households can double the chances a child develops pneumonia and makes recovery less successful.6 One of the underlying reasons for why this is the case is that the small polluting particles impair the immune system’s ability to fight and clear the infection.
Laura Jones et al. (2011) reviewed studies which assessed the impact of secondhand smoke on children, and concluded that children who live in households with smoking parents are more likely to acquire pneumonia as well as other respiratory illnesses. A Global Burden of Disease study by Mattias Öberg et al. has estimated that in 2004, globally around 40% of children lived in households where at least one close relative smoked.7
The same study suggested that exposure to secondhand smoke led to 165,000 deaths among children under 5 from lower respiratory diseases that year.
Exposure to other pathogens such as measles and HIV also increases the risk of pneumonia in children. When children who are infected with HIV develop AIDS –which weakens their immune system – their chances of dying from pneumonia increase significantly. A study by Evropi Theodoratou et al., published in Lancet Infectious Diseases, found that children with HIV have a seven times greater risk of dying from pneumonia compared to those without it.8
The same study also showed that the proportion of child deaths from pneumonia that can be attributed to HIV varies widely between countries: in 2010 only 1% of all child deaths from pneumonia in India could be directly attributed to HIV, compared to 64% in Swaziland and 62% in Lesotho. In Africa, a total of 3% of cases and 17% of all childhood deaths from pneumonia was attributable to HIV. These regional differences are important to know so that interventions that can save most lives can be prioritised.
Pneumonia is not an easily transmittable disease, it requires close contact for the pathogens to be transmitted to another person via air droplets. Therefore overcrowding – too many people living in one space – also increases the risks of pneumonia. This is yet another reason why pneumonia is a disease of poverty: in 2015, 47% of children in low and middle-income countries were living in overcrowded households.9
Despite progress against it, more than 800,000 children still die from pneumonia each year. We know where children are dying, and the factors that make them vulnerable to the disease. The key question is how we continue to make progress against it.
The risk factors for developing pneumonia in people aged 70 and older are similar to the risk factors for children.
Small particulate matter air pollution poses the greatest risk contributing to more than 300,000 deaths from pneumonia in 2017.
Smoking and exposure to secondhand smoke have contributed to 150,000 and 73,000 deaths from pneumonia in this age group, respectively.
When we understand what risks are most likely to lead to children acquiring pneumonia, we can find ways to reduce them. Furthermore, because a number of risks factors for pneumonia overlap with risk factors for other diseases, especially diarrhea, interventions that target pneumonia have the additional benefit of helping to limit other diseases and saving more lives.
There are several versions of pneumococcal conjugate vaccine (PCV), which target different serotypes of S. pneumoniae — the bacterium responsible for most cases of pneumonia. The PCV vaccine is given to children under 24 months old. According to a study by Cheryl Cohen et al. (2017), PVC13, the current recommended PCV vaccine version, has 85% effectiveness against invasive infections caused by the specific strains the pneumococcal strains included in the vaccine formulation.10
It has been estimated that if PCV13 coverage in low income countries would reach the coverage of DTP3 vaccine, PCV13 could prevent 399,000 child deaths and 54.6 million pneumonia episodes annually.11 India (which has the highest number of child deaths from pneumonia) only introduced PCV13 in 2017 and the coverage is still very low — clearly the pneumococcal vaccine still has a lot of potential.12
Another vaccine widely used to protect children against both pneumonia is Hib vaccine. Hib immunizes children against Haemophilus influenzae type b, a leading cause of meningitis in children that is also responsible for around 2% of pneumonia deaths in under-5s. In 2015 there were around 0.9 million cases Hib-related pneumonia globally. Hib immunization provides around 70% protection against Hib-related pneumonia and 84% protection against meningitis in children.13
Encouraging mothers to breastfeed during the first 6 months of a child’s life has a positive impact on reducing child undernutrition, which in turn protects from infectious diseases such as pneumonia. According to Laura Lamberti et al. (2013), pneumonia mortality of children in developing countries who are not breastfed in the first 5 months of their lives is 15 times greater than those who exclusively received their mother’s milk.14 As the map shows, the number of infants who are exclusively breast fed is still low. Globally, an estimated 41% of infants were exclusively breastfed in 2017.15
There has been a significant progress in improving air pollution levels in recent decades. Death rates from indoor air pollution are falling as a result of improved access to cleaner fuels for heating and cooking. But there is still much progress to be made, especially in Sub-Saharan Africa, where in most countries less than 10% of households have access to clean fuels for cooking. And, whilst progress has been made on indoor air pollution, high levels of outdoor pollution remains a problem across many countries. Reducing air pollution levels could have added benefits by not only reducing pneumonia cases but also limiting incidence of asthma in children.16
A child with a suspected case of pneumonia (with symptoms of difficulty in breathing and coughing) should be taken to a healthcare provider so that correct and immediate treatment can be provided. Delay in seeking treatment can increase the chances of a child dying.17 However, as the map shows, seeking healthcare is still not as common as it should be. Globally, less than two-thirds of children with symptoms of pneumonia were taken to a healthcare provider in 2016. This figure is even lower in places where healthcare is most needed — just 47% in Sub-Saharan Africa.18
Given that most cases of pneumonia are of bacterial origin, antibiotics are the general course of treatment. Due to the lack of resources, in places where pneumonia cases are most common, a quick diagnosis for the cause of disease is not always possible. Given the potential high risk of death from untreated pneumonia, the World Health Organisation (WHO) recommends antibiotic treatment depending on the disease symptoms and its severity before the cause of disease is available. Amoxicillin, ampicillin and gentamicin are the most commonly used antibiotics to treat pneumonia.19 20
During pneumonia, alveoli in the lungs get filled with pus and fluid, which prevents oxygen from being transferred to blood. Consequently, a condition known as hypoxaemia — the lack of oxygen – can develop. When a child with pneumonia develops hypoxaemia the risk of dying increases five-fold.21 Treatment with oxygen therapy (supplying oxygen-enriched air to the patient)22 is one way to mitigate hypoxaemia.23 A study from Papua New Guinea has shown that oxygen therapy can reduce the risk of death from severe pneumonia by 35%. However, the need for a specialist equipment to diagnose and treat hypoxaemia still poses a substantial barrier in low-resource settings. Since 2017, the WHO includes oxygen in its List of Essential Medicines.24 Improved access to oxygen could save the lives of 120,000 children annually.25
There are a number of ways we could reduce the number of children dying from pneumonia, including eliminating the major risk factors such as undernutrition and air pollution, and providing better access to treatment.
But we have another highly effective intervention: a vaccine against the major pathogen responsible for pneumonia in children. Streptococcus pneumoniae is the leading cause of pneumonia in children under 5 — it was responsible for 52% of all fatal pneumonia cases in children in 2016.26 Pneumococcal vaccines are vaccines that target S. pneumoniae bacteria. Here we look at their effectiveness and how we can maximise the number of children they save.
Since the World Health Organisation (WHO) started recommending including pneumococcal vaccines in national immunisation programmes for children in 2007, there has been a progressive increase in the number of countries using the vaccine. You can see the uptake in the vaccine across the world using the ‘play’ button on the map below.
But the coverage of pneumococcal vaccines is still low in many countries. In India and Nigeria – the two countries with the greatest number of childhood deaths from pneumonia in 2017 – only 44% and 58% of one-year-olds are vaccinated, respectively. In 2018, less than half (47%) of one-year-olds in the world received the full course of pneumococcal vaccination. This means that 55 million children who could be protected by the vaccine are still waiting for it — an appallingly high number for a vaccine that not only protects from pneumonia, the leading cause of childhood death, but also a range of other diseases (as we’ll discuss below). 27
S. pneumonia, simply referred to as pneumococcus, is a bacterium that is often found living in the upper respiratory tract of healthy people. Generally, the bacterium is harmless or causes milder illnesses such as bronchitis, sinusitis, and ear infections. Pneumococcal vaccines are effective against these milder illnesses but also protect from what is called pneumococcal invasive disease (PID). PID occurs when the pneumococcus moves from colonizing the upper respiratory tract to colonizing sites that are normally sterile, such as blood, cerebrospinal fluid or pleural cavity (fluid-filled space surrounding the lungs).28 Bacterial invasion leads to life-threatening diseases such as sepsis, meningitis and severe pneumonia.
There are two types of pneumococcal vaccines available: conjugated polysaccharide pneumococcal vaccine (PCV) and non-conjugated polysaccharide pneumococcal vaccine (PPSV). Both vaccines are designed to elicit immune responses against multiple serotypes of pneumococcus, which are defined by the different immune responses to the sugars found on the bacterial surface.29 To be broadly effective, the vaccines need to protect against a certain number of these pneumococcal serotypes but it is not necessary to include all possible serotypes because only a limited subset is responsible for 70%-80% of invasive pneumococcal disease.30 However, as we’ll discuss later, this variety of different pneumococcal serotypes is important to keep in mind because as vaccine coverage increases we may see a replacement of the vaccine-included serotypes with the less dominant ones, which will mean new vaccine versions will be required.
While there are two types of pneumococcal vaccines available, for children under two years old only the conjugated (i.e. PCV) vaccines are recommended because the non-conjugated versions (i.e. PPSV) are not effective at such a young age.31
In clinical trials PCV has shown 80% efficacy in reducing invasive pneumococcal disease caused by the bacterial serotypes included in the vaccine formulation. Vaccinated children are 27% less likely to be diagnosed with pneumonia and 11% less likely to die from it. 32
Several studies have attempted to estimate how many lives PCV vaccination has and could save. One Lancet study concluded that between 2000 and 2015, in 120 countries the number of childhood deaths caused by pneumococcus fell from 600,000 to 294,000 — a decline of 54%. Most of this decline was attributed to the PCV vaccines: over this period, it’s estimated they saved the lives of 250,000 children. The majority of these deaths were from pneumonia, but they also include deaths prevented from pneumococcal meningitis and other diseases.33
How many lives pneumococcal vaccination could be saving? The chart shows how powerful pneumococcal vaccine could be. It is based on a recent study published in The Lancet Global Health journal, which calculated that if the PCV vaccine coverage would reach at least the levels of diphtheria, tetanus and pertussis vaccine (DTP3), we could save the lives of 399,000 children under 5 and prevent 54.6 million pneumonia episodes annually.34 This number was calculated compared to no PCV vaccination at all, which means that some of these lives are already being saved in countries that use PVC vaccination. However, in many countries PCV vaccination rates still fall far below the DTP3 rates, indicating that we still haven’t used the pneumococcal vaccine to its full potential.
A continued increase in immunisation coverage and introduction of PCV vaccines into countries which don’t already have them is important if we want to make use of the full potential of pneumococcal vaccines.
PCV vaccines are amongst the most expensive vaccines in national immunisation programmes. The price ranges from $3.05 per dose in GAVI35 supported low-income countries to $169 in high-income countries such as the United States.36 For low-middle-income countries who are transitioning from GAVI support the increasing future costs of vaccination place a considerable strain on national healthcare budgets.37
But given the high burden of pneumococcal diseases, even at high prices, PCV vaccines are considered to be cost-effective, with an estimated return of investment in low- and middle-income countries of around 3.38
PCV vaccines include a limited subset of possible pneumococcal serotypes. The distribution of pneumococcal serotypes is known to vary between countries and PCV vaccines include the globally most common ones. Depending on how common the non-vaccine serotypes are in individual countries, it may affect the potential for vaccine’s impact. However, not all countries collect data on serotype distribution to be able to assess this impact.39 40 41 Notably, since the PCV vaccine was introduced, there has been a rise in pneumococcal invasive disease incidences caused by the less common serotypes. This suggests that, by reducing the prevalence of vaccine-included serotypes, the vaccine unintentionally provides space for non-vaccine serotypes, against which it works less well.42 This means that if the serotype formulation of PCV is not continually reevaluated, over time its effectiveness may decrease. In the future, new versions of pneumococcal vaccines may be needed that work better independently of the bacterial serotype. Such vaccines are already in development.43 44
The research literature uses the terms pneumonia and lower respiratory infections (LRIs) interchangeably. The Institute for Health Metrics and Evaluation (IHME) provides mortality data on LRIs, which they define as pneumonia caused by a range of different pathogens, though they also include bronchiolitis in this category.45 46 In this entry we use data provided by IHME as an estimate for the deaths from pneumonia. While cases of bronchiolitis are quite common they are generally not fatal, therefore, it is reasonable to assume that most of IHME data refers to cases of clinical pneumonia.
Clinical pneumonia (also called WHO-pneumonia) is pneumonia that is diagnosed by symptoms (fast breathing and coughing). Symptoms-based definition inevitably means that diseases with similar symptoms may be misdiagnosed as clinical pneumonia.
Ideally, pneumonia would always be diagnosed by a physician using radiological imaging and by determining the causative agent. However, because such diagnosis requires a lot of resources, it is often not possible to do. Puumalainen et al. study from 2008 has found that 34% of clinically diagnosed pneumonia cases have radiographic evidence of pneumonia and 11% had a diagnosable bacterial cause.47
Pneumonia is an infection of the lower respiratory tract that can be caused by multiple microbial pathogens.
By far the most common cause of pneumonia in unvaccinated children is an infection by a bacterium called Streptococcus pneumoniae, simply referred to as pneumococcus. The Global Burden of Disease (GBD) study from 2018 has estimated that pneumococcus was responsible for 52% of fatal pneumonia cases in children in 2016.48
Other pathogens which cause pneumonia in children are Haemophilus influenzae type b, respiratory syncytial virus (RSV), and the influenza virus. Each of these pathogens was responsible for less than 4% of lethal pneumonia cases in 2016.49 Despite being minor causes, it’s important to continue developing treatments against these pathogens; they will become increasingly important as vaccination coverage for the most common causes increases. According to a study by Katherine O’Brien et al. (2019), when children are routinely vaccinated with pneumococcal and Hib vaccines, as many as 62% of pneumonia cases are caused by viral pathogens such as RSV.50
Children can contract pneumonia in a number of ways. Pneumococcus and H. influenzae are bacteria that can be found in the upper respiratory tract of healthy individuals without any symptoms. Under circumstances when the conditions in the upper respiratory tract are compromised51 these normally benign bacteria may move to lower respiratory tract where they lead to pneumonia.52
Pneumonia caused by bacterial and viral pathogens can be contagious and transmitted when a person coughs or sneezes, however, sensible precautions such as sanitising hands and surfaces, wearing a face mask if available and limiting close contact with a sick person can significantly limit the chances of transmission.