As America went into lockdown and treatment centers closed their doors, drug overdose deaths in the United States jumped by nearly a third last year, new data show.

The estimated 93,331 drug overdose deaths recorded during 2020 are a sharp increase -- a 29.4% rise -- over the 72,151 deaths estimated in 2019, according to preliminary data from the National Center for Health Statistics (NCHS). The NCHS is part of the U.S. Centers for Disease Control and Prevention.

Dr. Nora Volkow, director of the National Institute on Drug Abuse, called the new numbers "chilling."

""This is the highest number of overdose deaths ever recorded in a 12-month period, and the largest increase since at least 1999," she said. "The COVID-19 pandemic created a devastating collision of health crises in America."

The new NCHS data also show that overdose deaths from opioids, specifically, spiked from 50,963 in 2019 to 69,710 in 2020, about a 27% rise.

Overdose deaths from synthetic opioids (primarily fentanyl) and psychostimulants such as methamphetamine also rose from 2019 to 2020, the report found. There were also increases in deaths from semi-synthetic opioids such as prescription pain medications and from cocaine.

Volkow, who wasn't involved in the new report, said the sharp and tragic rise in overdoses stems from a combination of factors.

"This has been an incredibly uncertain and stressful time for many people and we are seeing an increase in drug and care medical supplies consumption, difficulty in accessing lifesaving treatments for substance use disorders, and a tragic rise in overdose deaths," she said.

Dr. Teresa Murray Amato has seen cases of overdose firsthand in her role as chair of emergency medicine at Long Island Jewish Forest Hills, in New York City.

"Personally I have notice many patients complaining about insomnia, increased anxiety and struggles with drug misuse as a means of self-medicating," she said. "If you or a loved one are concerned about drug misuse, please reach out to your doctor and make a safe plan."

Amato believes factors other than COVID may have been at play. "Over the past year we have also seen increased social unrest, leading to general increased anxiety as people are exposed to violent images in the news more frequently," she said.

Another expert said COVID fears kept many from seeking help.

Some people "avoided seeking care for mental health or substance use problems – despite the fact that healthcare providers, including our own hospital, began to evaluate, admit and treat patients remotely wherever possible, in order to remove barriers to access," said Dr. Timothy Sullivan, chair of psychiatry and behavioral sciences at Staten Island University Hospital in New York City.

"Most opioid treatment programs, such as methadone programs, radically changed their policies regarding provision of take-home bottles, for instance, in order to facilitate access," he added.

All the experts agreed that access to timely health care is crucial.

"As we continue to address both the COVID-19 pandemic and the opioid crisis, we must prioritize making treatment options more widely available to people with substance use disorders," Volkow said.

The new NCHS data included reported and predicted drug overdose deaths nationally and in each jurisdiction, as well as reported and predicted drug overdose deaths involving specific drugs or drug classes.