WITH NEARLY 15 million coronavirus cases and more than 280,000 deaths in the U.S., we have fortunately learned much about COVID-19 prevention measures and treatments since the early days of the pandemic, and a vaccine is now in sight. Much of our knowledge concerns risk factors for worse outcomes, which include older age, diabetes, high blood pressure and immunocompromised status.

Yet one risk factor remains hidden in plain sight, or is at least perceived as unimportant: obstructive sleep apnea.

Recent research has confirmed an association between OSA – a disorder in which a person’s upper airway intermittently closes during sleep and hinders their breathing – and severe illness from COVID-19. A study published earlier this fall concluded that patients with OSA were eight times more likely to be infected with COVID-19 than others of similar age who’d received care from a Chicago-area health system. The condition also was associated with increased risk of hospitalization and twice the risk of respiratory failure. Another recent study analyzed data on more than 4,500 patients with COVID-19 and found that those with sleep apnea had an increased rate of all-cause mortality.

The implications are huge. In the U.S., more than 54 million adults are estimated to have OSA. Yet according to a report from the American Academy of Sleep Medicine, only a small fraction of those with the condition are diagnosed. Worldwide, the estimated prevalence of OSA reaches nearly 1 billion adults 30 to 69 years old. That equates to a billion people with not only varying degrees of snoring, poor sleep quality, fatigue and memory difficulties, but who also have a chronic, treatable medical condition that puts them at higher risk for severe COVID-19 illness.

Notably, OSA also has been associated with cardiovascular events such as heart attack and stroke, erectile dysfunction, dementia, depression and occupational and motor vehicle accidents. Its underdiagnosis has been labeled part of a “hidden health crisis,” as it cost the U.S. an estimated $150 billion in 2015.

Certain populations – including African Americans and Hispanics – are disproportionately affected. Women, even if they have classic symptoms like snoring and sleepiness, are often underdiagnosed and less likely to be referred for evaluation and treatment, despite evidence of health-related risks. OSA in pregnancy has been associated with poor maternal health outcomes; however data is needed to develop evidence-based, pregnancy-specific guidelines for the screening and treatment of pregnant patients with OSA.

Despite the larger number of patients affected and the increasing knowledge of OSA’s profound negative implications, a drastic shortage of board-certified sleep medicine physicians remains, with approximately one sleep specialist for every 40,000 Americans. Approximately 45% of accredited U.S. medical schools have a sleep medicine fellowship, and the influx of new sleep physicians is insufficient and unevenly distributed to larger metropolitan areas.

Here is my call: In the short term, funding for continued research is paramount to assess the impact of OSA treatment on risk for severe COVID-19 illness, as a lack of treatment has been linked to higher COVID-19 prevalence, signaling a modifiable risk factor. We also need to educate patients about OSA’s link to severe COVID-19 illness, using venues like the media, community outreach events and virtual activities. This effort needs to aim for health equity and include racial and ethnic minority groups who are at disproportionate risk from COVID-19. With patients as partners, more people can seek evaluation and treatment sooner.