A heroin user prepares to shoot up on the street in a South Bronx neighborhood which has the highest rate of heroin-involved overdose deaths in the city on October 7, 2017 in New York City. | Spencer Platt/Getty Images

An Opioid Vaccine Developed by the US Military Could Combat Addiction

Life expectancy in the United States declined for the second year in a row due to an opioid epidemic, but a new vaccine shows promising results in mice and rats.