Hypertension Heightens Risk for Severe
COVID-19, Even in the Fully Vaxxed

Heidi Splete

July 27, 2022

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Adults with hypertension who were vaccinated for COVID-19 with at least one booster were more than twice as likely as vaccinated and boosted individuals without hypertension to be hospitalized for severe COVID-19, according to data from more than 900 individuals.

"We were surprised to learn that many people who were hospitalized with COVID-19 had hypertension and no other risk factors," said Susan Cheng, MD, MPH, director of the Institute for Research on Healthy Aging in the department of cardiology at the Smidt Heart Institute, Los Angeles, and a senior author of the study. "This is concerning when you consider that almost half of American adults have high blood pressure."

COVID-19 vaccines demonstrated ability to reduce death and some of the most severe side effects from the infection in the early stages of the pandemic. Although the Omicron surge prompted recommendations for a third mRNA vaccine dose, "a proportion of individuals who received three mRNA vaccine doses still required hospitalization for COVID-19 during the Omicron surge," and the characteristics associated with severe illness in vaccinated and boosted patients have not been explored, Joseph Ebinger, MD, of Cedars-Sinai Medical Center, Los Angeles, and colleagues wrote.

Previous research has shown an association between high blood pressure an increased risk for developing severe COVID-19 compared to several other chronic health conditions, including kidney disease, type 2 diabetes, chronic obstructive pulmonary disease, and heart failure, the researchers noted.

In a study published in Hypertension, the researchers identified 912 adults who received at least three doses of mRNA COVID-19 vaccine and were later diagnosed with COVID-19 during the surge in infections from the Omicron variant between December 2021 and April 2022.

A total of 145 of the individuals were hospitalized (16%); of these, 125 (86%) had hypertension.

Patients with hypertension were the most likely to be hospitalized, with an odds ratio of 2.9. In addition to high blood pressure, factors including older age (OR, 1.3), chronic kidney disease (OR, 2.2), prior myocardial infarction or heart failure (OR, 2.2), and longer time since the last vaccination and COVID-19 infection were associated with increased risk of hospitalization in a multivariate analysis.

However, the increased risk of severe illness and hospitalization associated with high blood pressure persisted, with an OR of 2.6, in the absence of comorbid conditions such as type 2 diabetes, kidney disease, and heart failure, the researchers emphasized.

"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, which may contribute to greater disease severity," they wrote.

The findings were limited by several factors, including the use of data from a single center and lack of information on which Omicron variants and subvariants were behind the infections, the researchers noted.

However, the results highlight the need for more research on how to reduce the risks of severe COVID-19 in vulnerable populations, and on the mechanism for a potential connection between high blood pressure and severe COVID-19, they said.

Given the high prevalence of hypertension worldwide, increased understanding of the hypertension-specific risks and identification of individual and population-level risk reduction strategies will be important to the transition of COVID-19 from pandemic to endemic, they concluded.

Omicron Changes the Game

"When the pandemic initially started, many conditions were seen to increase risk for more severe COVID illness, and hypertension was one of those factors — and then things changed," lead author Ebinger said in an interview. "First, vaccines arrived on the scene and substantially reduced risk of severe COVID for everyone who received them. Second, Omicron arrived and, while more transmissible, this variant has been less likely to cause severe COVID. On the one hand, we have vaccines and boosters that we want to think of as 'the great equalizer' when it comes to preexisting conditions. On the other hand, we have a dominant set of SARS-CoV-2 subvariants that seem less virulent in most people.

"Taken together, we have been hoping and even assuming that we have been doing pretty well with minimizing risks. Unfortunately, our study results indicate this is not exactly the case," he said.

"Although vaccines and boosters appear to have equalized or minimized the risks of severe COVID for some people, this has not happened for others — even in the setting of the milder Omicron variant. Of individuals who were fully vaccinated and boosted, having hypertension increased the odds of needing to be hospitalized after getting infected with Omicron by 2.6-fold, even when accounting for or in the absence of having any major chronic disease that might otherwise predispose to more severe COVID-19 illness," Ebinger added.

"So, while the originally seen risks of having obesity or diabetes seem to have been minimized during this current era of pandemic, the risk of having hypertension has persisted. We found this both surprising and concerning, because hypertension is very common and present in over half of people over age 50."

Surprisingly, "we found that a fair number of people, even after being fully vaccinated plus a having gotten a booster, will not only catch Omicron but get sick enough to need hospital care," Ebinger emphasized. "Moreover, it is not just older adults with major comorbid conditions who are vulnerable. Our data show that this can happen to an adult of any age and especially if a person has only hypertension and otherwise no major chronic disease."

The first takeaway message for clinicians at this time is to raise awareness, Ebinger stressed in the interview. "We need to raise understanding around the fact that receiving three doses of vaccine may not prevent severe COVID-19 illness in everyone, even when the circulating viral variant is presumed to be causing only mild disease in most people. Moreover, the people who are most at risk are not whom we might think they are. They are not the sickest of the sick. They include people who might not have major conditions such as heart disease or kidney disease, but they do have hypertension."

Second, "we need more research to understand out why there is this link between hypertension and excess risk for the more severe forms of COVID-19, despite it arising from a supposedly milder variant," said Ebinger.

"Third, we need to determine how to reduce these risks, whether through more tailored vaccine regimens or novel therapeutics or a combination approach," he said.

Looking ahead, "the biological mechanism underpinning the association between hypertension and severe COVID-19 remains underexplored. Future work should focus on understanding the factors linking hypertension to severe COVID-19, as this may elucidate both information on how SARS-CoV-2 effects the body and potential targets for intervention," Ebinger added.

The study was supported in part by Cedars-Sinai Medical Center, the Erika J. Glazer Family Foundation, and the National Institutes of Health. The researchers had no financial conflicts to disclose.

This article originally appeared on MDedge.com, part of the Medscape Professional Network.

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