According to the World Health Organization (WHO), the only thing that works better than vaccines in reducing the human and economic costs of infectious diseases is clean water.
That certainly seems to be the case for pneumococcus and Hib, the two leading bacterial causes of pneumonia and meningitis. A new study published this week (June 11) in The Lancet Global Health estimates that, between 2000 and 2015, two types of vaccines that protect against both Hib and pneumococcus—the pneumococcal conjugate vaccine (PCV) and the Haemophilus influenzae type b (Hib) vaccine—have collectively saved the lives of more than 1.4 million children aged one to 59 months, or just under five years old (the age group determined by the researchers to be the most relevant to the study and the most helpful to policymakers).
The study, conducted by scientists at the Johns Hopkins Bloomberg School of Public Health and funded by the Bill & Melinda Gates Foundation, focused on Hib and pneumococcus because they can cause meningitis, pneumonia, sepsis, and other serious health complications that contribute to the high rates of child mortality in developing countries. According to the study, in 2000, about 900,000 children worldwide died from infections related to the bacteria—most of them from pneumonia. In 2015, the estimate was 323,500 children.
The researchers hope that this latest data can lead to smart public health planning that will eventually eliminate preventable deaths from pneumococcus and Hib.
In most parts of the world, pneumococcus and Hib are not deadly killers. In fact, Hib disease has been virtually eliminated and pneumococcal disease has been dramatically reduced in the US and many European countries. The bacteria are not equal opportunity killers: According to the study, approximately 50% of all pneumococcal deaths in 2015 occurred in just four countries—India, Nigeria, the Democratic Republic of the Congo, and Pakistan. Introducing and expanding access to PCV and Hib vaccines in these four countries could have a disproportionate impact on the global death toll of the bacteria, according to Brian Wahl, the lead author of the study.
The researchers were able to show that the vaccines, and not other factors like better sanitary conditions, were directly responsible for the reduction in the burden of disease from Hib and pneumococcus. In 2010, 52 countries eligible for vaccine funding support from GAVI—a public-private partnership that provides vaccines to developing countries—introduced PCV in their national immunization programs. By the end of 2015, 129 countries were using PCV, and pneumococcal deaths, which had declined 3% per year between 2000 and 2010, began declining 8% per year between 2010 and 2015. The researchers found that pneumococcal deaths declined by 51% and Hib deaths by 90% from 2000 to 2015. They concluded that “the widespread use of Hib vaccine and the recent introduction of PCV in countries with high child mortality is associated with reductions in Hib and pneumococcal cases and deaths.”
Still, the researchers acknowledge that their calculations “may have overestimated the impact of vaccination in children, particularly for PCV, due to the limited availability of data.” That’s because reporter coverage data from some countries is likely overestimated at the administrative level.
The biggest impact is yet to come. Of the four countries where half of all pneumococcal deaths occur, Pakistan and the Democratic Republic of the Congo introduced PCV in 2012, Nigeria began routine immunization with PCV in 2014, and India started routine use in three states in 2017. The more PCV coverage expands, the more global pneumococcal deaths will decrease.
The study’s hopeful conclusion that a leading cause of child mortality could soon be eradicated thanks to two efficient vaccines stands in stark contrast to another study released this week (June 12) in PLOS Medicine, which shows that non-medical, “philosophical-belief” exemptions from childhood vaccinations are rising in some areas of the United States, creating a risk of vaccine-preventable disease outbreaks. That’s largely due to what the World Health Organization calls a “vociferous anti-vaccine lobby” which “thrives today in spite of the undeniable success of vaccination programs against formerly fearsome diseases that are now rare in developed countries.”
The fact that pneumococcus and Hib mostly kill under-privileged children in developing countries perhaps explains why medical professionals have little patience for the increasingly vocal anti-vaccine lobby. ”It’s unfortunate that exemptions in the US are on the rise,” Wahl told Quartz. “It not only puts children who are not getting vaccinated at risk, but it also puts children who, for whatever reason, can’t be vaccinated, at risk as well.”
In dealing with vaccines that save as many lives as PCV and the Hib vaccine have, he says, the concerns of the anti-vaccine lobby can seem out of touch with reality. “When you don’t see the disease and the toll that it takes on children and on families,” he said, “it’s easy to forget the value of vaccines and the power that they hold.”