Routine vaccines have prevented the deaths of about 154 million children around the world over the past 50 years, a new study shows, but efforts have been slowing recently, allowing for the growth of some vaccine-preventable diseases. This backslide could lead to many more unnecessary illnesses and deaths without an increased effort to vaccinate children and counter misinformation.

The report, published Tuesday in the medical journal The Lancet, says that over the past five decades, the World Health Organization’s Expanded Programme on Immunization has vaccinated more than 4 billion children. This doubling of global coverage of vaccines has prevented countless cases of tuberculosis, measles, polio, diphtheria, tetanus and pertussis.