Researchers hope the vaccine, which blocked the drug from entering rats’ brains, could help reduce overdoses in humansDrug overdose fatalities soared to a record high during the early Covid-19 pandemic. In 2020, deaths from overdoses in the United States rose to 91,799, a 30 percent spike from the previous year. Researchers say synthetic opioids such as fentanyl are partially responsible. These drugs were involved in more than half all fatal overdoses in 2020. More than 150 people die every day from synthetic opioids. “Fentanyl is killing Americans at an unprecedented rate,” Anne Milgram, administrator of the Drug Enforcement Administration, said...