People who have high blood pressure and Omicron-variant COVID-19 are at more than double the risk for hospitalization—even if they received three mRNA vaccine doses, according to a single-center study published yesterday in Hypertension.
Cedars-Sinai Medical Center researchers studied 912 people in Los Angeles who tested positive for COVID after receiving at least three mRNA COVID-19 vaccine doses from Dec 1, 2021, to Apr 20, 2022. A total of 145 (15.9%) were hospitalized, 125 (86.2%) of whom had high blood pressure (hypertension).
Since Omicron was first identified in the United States in December 2021, seven subvariants have been detected; the study didn't differentiate among them.
Risk factors for hospitalization included hypertension, older age, chronic kidney disease (CKD), heart attack (myocardial infarction [MI] or heart failure [HF]), and a longer interval between the last vaccine dose and infection.
Hypertension, which carried a 2.6-fold increased risk, superseded all other risk factors in importance—even after excluding patients with CKD, MI, or HF and those taking an angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB). Other previously identified risk factors for severe COVID-19, such as obesity and diabetes, weren't as strongly linked to hospitalization amid Omicron.
"Our results indicate persistence and even accentuation of hypertension-related risk in the setting of a more transmissible albeit generally less virulent strain," the researchers wrote. "Although the mechanism for hypertension-associated COVID-19 risk remains unclear, prior studies have identified delayed SARS-CoV-2 viral clearance and prolonged inflammatory response among hypertensive patients."
They noted that the implications of the findings are substantial given that nearly half of US adults have high blood pressure. "These findings were expected considering that these are chronic medical conditions that are well established to be associated with worse outcomes," first author Joseph Ebinger, MD, said in a Cedars-Sinai news release.
But what wasn't expected, Ebinger said, was that the risk of poor COVID-19 outcomes amid Omicron doesn't affect only older people with underlying illnesses. "Breakthrough Omicron infection severe enough to cause hospitalization can happen to an adult of any age, especially if a person has high blood pressure, even if they have no other major chronic disease," he said in an American Heart Association (AHA) news release.
"The people who are most at risk are not necessarily who we think they are. They are not the sickest of the sick, and this was a surprising finding."
People with hypertension and COVID-19 should talk with their physician about antiviral therapy to reduce their risk of hospitalization, Ebinger said in the Cedars-Sinai release. "The take-home message is that avoiding infection is extremely important—even when the circulating viral variant is presumed to cause mild disease in most people."
The study results could also help elucidate SARS-CoV-2's mechanisms, senior author Susan Cheng, MD, MPH, said in the Cedars-Sinai release. "Uncovering why hypertension is linked to COVID-19 could help us better understand how SARS-CoV-2 affects the body and provide clearer targets for prevention and treatment," she said.
In the AHA release, Ebinger called for raising awareness that three COVID-19 vaccine doses may not be enough to prevent severe infection in everyone, particularly those with hypertension. "We also need more research to understand why there is this link between high blood pressure and an excess risk for more severe COVID-19 illness," he added.