Another day, another study on the life-saving benefits of vaccines.

This time researchers analyzed the impacts of vaccines across 41 low- and middle-income countries, calculating the number of future deaths averted and the number of households that will have avoided the “medical impoverishment” that can come with vaccine-preventable disease. They found that vaccines protecting against just 10 diseases will prevent tens of millions of future deaths, with the poorest communities experiencing the greatest benefits. They also estimated vaccines will prevent about 24 million cases of medical impoverishment, which is defined by out-of-pocket spending on medical care and loss of income due to illness.

To conduct the study, published this month in Health Affairs, researchers examined vaccines against 10 disease-causing antigens: measles, hepatitis B, human papillomavirus (HPV), yellow fever, Hemophilus influenzae type b, Streptococcus pneumoniae, rotavirus, rubella, Neisseria meningitides serogroup A and Japanese encephalitis. They calculated future health gains and household financial impacts in 41 poor and middle-income countries (accounting for 1.52 billion people) between 2016 and 2030. Overall, the study estimated that the vaccines will have averted about 36 million deaths.

Vaccines against measles, hepatitis B and HPV (a sexually transmitted disease that causes cervical cancer) accounted for the biggest share of averted deaths, at 61 percent, 18 percent and 7 percent, respectively. Vaccines against Japanese encephalitis and Neisseria meningitides serogroup A (the bacterium that causes meningococcal disease) prevented fewer future deaths, as those vaccines are typically only used in certain regions. Immunization against rubella also had a smaller impact because the disease already has a low mortality rate.

Researchers found that while the poorest countries will experience the greatest number of deaths due to vaccine-preventable disease, they also reaped the greatest benefits from life-saving immunizations. In other words, the benefits of vaccines were greater for the poorest people in the study cohort than for the richest. Study authors write:

Although the poorest quintiles experienced the lowest vaccine coverage rates, they enjoyed the most health benefits in terms of absolute number of averted deaths: The poorest quintile accounted for the largest share of deaths averted by all vaccines (23–34 percent), and the poorest two quintiles accounted for over half of the deaths averted by most vaccines.

Regarding the financial impacts, researchers projected that all the vaccines helped reduce medical impoverishment — across the 41 countries, 24 million cases of impoverishment will be avoided by 2030. That reduction represents about 9 percent of people in low-income nations whose incomes are less than $1.90 per day.

The hepatitis B vaccine is projected to have the biggest impact on decreasing impoverishment, followed by vaccines for measles and meningococcal disease. Not surprisingly, the majority of impoverishment declines occurred among the poorest people. Researchers noted that out-of-pocket health care spending is a critical factor in household poverty — in fact, the World Health Organization estimates that health care costs push about 150 million people into poverty every year.

The study concluded that vaccines are key in achieving international goals on poverty reduction and improved health: “With reducing poverty and improving equity on the global development agenda, sustained investments in vaccines could make a large contribution toward achieving the Sustainable Development Goals and universal health coverage.” Indeed, vaccines are already known as a “best buy” in public health, yielding returns many — many — times greater than their costs.

For a copy of the new study, visit Health Affairs.