The Drug Enforcement Agency relies on hospitals to identify nurses and doctors who misuse drugs such as morphine and fentanyl. But "only a fraction of those who are diverting drugs are ever caught."

Fentanyl-related drug overdose deaths increased 61.4% since March, preliminary data show.

"During the pandemic, basically everything is pointed in the wrong direction," says one federal health official, who calls the convergence of COVID-19 and America's addiction crisis "a nightmare."