A vaccine against bacterial pneumonia and another against meningitis have saved 1.45 million children's lives this century, according to a new study.
The diseases the vaccines prevent are now concentrated in a handful of countries where the medications are not yet widely available or were only recently introduced, the research says.
Pneumonia is the leading cause of death among children worldwide. The bacteria targeted by the shots, Haemophilus influenzae type b (known as Hib) and Streptococcus pneumoniae (pneumococcus), are major causes of pneumonia and also cause meningitis. Together, the two bacteria claimed nearly 1.1 million lives in 2000, before the vaccines were widely available, according to the World Health Organization.
Vaccines against the bacteria are not new, but funding to provide them in low-income countries only became available recently.
To estimate their impact, the researchers started with country-by-country data from the WHO on pneumonia and meningitis cases and deaths, as well as vaccine coverage estimates. They factored in data from dozens of clinical studies on infections caused by the two bacteria to create estimates of illness and death from the diseases in 2000 and 2015.
They found deaths from Hib fell by 90 percent in 2015, saving an estimated 1.2 million lives since 2000. Pneumococcus deaths fell by just over half, accounting for approximately 250,000 lives saved.
The research appears in the journal The Lancet Global Health.
"What was interesting was to see the rate at which some of these deaths have been prevented in the last several years," said lead author Brian Wahl at Johns Hopkins University, "largely due to the availability of funding for these vaccines in countries with some of the highest burdens [of disease]."
The study estimates that 95 percent of the reduction in pneumococcal deaths occurred after 2010, when 52 low- and middle-income countries began receiving funding from Gavi, The Vaccine Alliance, to introduce the vaccine into their national immunization programs.
"The good news is that the numbers are moving in the right direction," wrote Cynthia Whitney at the U.S. Centers for Disease Control and Prevention in an accompanying editorial.
However, Whitney added, "far too many deaths — about 900 every day — are still being caused by these two infections."
She notes that more than 40 percent of the world's children live in countries where pneumococcal vaccine is not a routine childhood immunization.
Many of the countries with the largest number of deaths from these two bacteria have recently introduced the vaccines, but coverage is uneven.
India, Nigeria, China and South Sudan had the highest rates of death from Hib, the study says. All but China have introduced the vaccine in the past few years.
Half of the world's pneumococcal deaths occurred in just four countries: India, Nigeria, the Democratic Republic of the Congo and Pakistan. All have recently introduced the vaccine, though in India it is a routine immunization in only three states.
Lowering the global burden of these diseases will depend on improving coverage in these countries, the study says.