People with substance use disorders may be more likely to become infected and die of COVID-19, according to a recent study funded by the National Institutes of Health and published in Molecular Psychiatry.
"Drugs inhibit the ability to fight viral and bacterial infections, disrupting immune function," Dr. Nora D. Volkow, director of the National Institute on Drug Abuse and co-author of the study, told ABC News.
"Opioids inhibit the respiratory centers in the brain. The combination of the two leads to the increased risk of COVID and its complications," she added.
Opioid epidemic meets the coronavirus
The Centers for Disease Control and Prevention estimated that more than 70,000 people died in the U.S. from an opioid overdose in 2019. These numbers are projected to be higher in 2020.
Overdose with opioids is caused by the respiratory depressant effects of these drugs. Opioids -- including but not limited to heroin, oxycodone, hydrocodone and fentanyl -- work by slowing down the breathing rate.
COVID-19 also affects breathing, decreasing the ability to properly take in oxygen, which makes the combination of opioids and COVID-19 infection particularly lethal.
Tobacco and cocaine increase risks too
In addition, the chronic use of drugs such as tobacco, cocaine and opioids is associated with heart problems, including risk for heart attacks and heart failure.
"Cocaine doesn't work in the same way opioids do. Stimulants, such as cocaine, work by causing constriction of blood vessels," said Volkow. Chronic cocaine use can lead to high blood pressure, which is also a risk factor for COVID-19 complications.
"All substance use is highly comorbid with tobacco use," which can leave you more vulnerable to respiratory illnesses, added Volkow.
The U.S. Food and Drug Administration warns that smoking cigarettes can cause heart and lung disease and people with underlying heart and lung problems may have increased risk for serious complications from COVID-19.
"Smoking can also cause inflammation and cell damage in the body, and can weaken your immune system, making it less able to fight off disease," they add.
The pandemic has led to an increase in many risk factors for substance addiction, including isolation, financial hardship and mental health problems. The need for treatment services has gone up significantly while mental health and addiction treatment centers have struggled to stay open. Financial burdens caused by safety regulations, quarantine rules, limited capacity and fewer physician referrals are only some of the reasons these centers have been having a hard time staying afloat.
Disruptions in treatment caused by the pandemic
The CDC noted on its website that the COVID-19 pandemic has caused disruptions in treatment.
In-person treatment options might not be available, which may bring on a relapse for those in remission. Narcotics Anonymous meetings, for instance, were suspended early in the pandemic, just when support was perhaps needed most, and the transition to online meetings was slow. Now they're beginning to open up, offering social support and mentorship that are often fundamental to recovery.
Syringe service programs may be closed or have reduced hours, limiting access to clean syringes, constituting a public health hazard. Illicit drug supplies might be limited, or access disrupted due to social distancing, which can potentially lead to the risk of using contaminated drug products that might increase overdoses or other adverse reactions.
In addition, social distancing rules and stay-at-home mandates may lead to higher numbers of people using substances alone, without others around to administer life saving remedies such as naloxone or to call for help in the case of overdose.
"It is very important for substance users to recognize that they are at a higher risk," said Volkow.
The study emphasizes the need to screen for, and treat, substance use as part of the plan for controlling the pandemic.
It is important for health care providers to closely monitor patients with substance use and develop a plan to help protect them from infection and severe outcomes, the study concludes.
Find a health care provider or treatment for substance use disorder and mental health: SAMHSA's National Helplineexternal icon: 1-800-662-HELP (4357) and TTY 1-800-487-4889
Yalda Safai, M.D., M.P.H., is a psychiatry resident in New York City and contributor to ABC News' Medical Unit.