The findings identify clinical and laboratory factors associated with severe illness and death, but they do not establish that any factor caused the observed outcomes. The researchers analyzed demographic and clinical data from patients admitted between April and June 2022, focusing on the characteristics and prognosis of hypertensive patients infected with the BA.2 variant. The study population was limited to hospitalized cases treated at one institution, rather than all people infected in Shanghai or the wider population.

Multivariable logistic regression was used to assess associations between patient characteristics, treatments, laboratory results and clinical status on one hand, and either moderate or severe disease or mortality on the other. All reported odds ratios therefore describe model-based associations within this cohort. For the clinical classification of COVID-19, vaccination was associated with lower odds of moderate or severe disease.

The reported odds ratio was 0.280, with a 95% confidence interval of 0.143–0.548. A higher lymphocyte count was also associated with lower odds, with an odds ratio of 0.608 and a 95% confidence interval of 0.411–0.898. In the opposite direction, pulmonary infection was associated with substantially higher odds of moderate or severe disease, with an odds ratio of 5.422 and a 95% confidence interval of 2.789–10.542.

Elevated high-sensitivity C-reactive protein, or hs-CRP, had a smaller but statistically significant association with increased odds of moderate or severe disease. The reported odds ratio was 1.006, with a 95% confidence interval of 1.001–1.011. Together, these results indicate that pulmonary involvement, vaccination status, lymphocyte count and hs-CRP were independently associated with the study’s clinical classification of disease severity.

They do not demonstrate that vaccination or any laboratory measure prevented severe COVID-19. The mortality model identified a different set of independent associations. Chronic kidney failure was associated with the largest reported point estimate for death, with an odds ratio of 5.701 and a wide 95% confidence interval of 1.638–19.842.

Theophylline treatment was also associated with increased odds of death, with an odds ratio of 5.063 and a 95% confidence interval of 1.818–14.101. Elevated D-dimer was associated with modestly higher odds of death, with an odds ratio of 1.092 and a 95% confidence interval of 1.002–1.190. The confidence intervals for kidney failure and theophylline were broad, indicating substantial uncertainty around their point estimates.

Two immune-nutritional measures were associated with lower odds of mortality. A higher lymphocyte proportion had an odds ratio of 0.920, with a 95% confidence interval of 0.865–0.977, while higher albumin had an odds ratio of 0.865, with a 95% confidence interval of 0.793–0.944. These estimates describe the relationships detected after multivariable adjustment.

They do not show that increasing lymphocyte proportion or albumin would reduce the risk of death. The findings suggest that the prognosis of BA.2 infection among hospitalized patients with hypertension did not follow a single pattern. Although 86.7% of the hypertensive subgroup had asymptomatic or mild illness, the analysis distinguished patients with clinical and laboratory indicators associated with greater risk.

Several limitations constrain how the results can be interpreted. The retrospective design leaves the analysis vulnerable to the clinical characteristics and treatment decisions of hospitalized patients, while the single-center setting restricts generalizability to patients treated elsewhere. The cohort also covered a limited period, and the results do not establish population incidence, the probability of BA.2 infection among hypertensive people or outcomes among those not admitted to hospital.

Although the data are consistent with vaccination being associated with lower odds of moderate or severe disease, the observational analysis cannot separate that association from other patient differences. The study likewise does not establish that theophylline itself increased mortality risk. For people with hypertension infected during the BA.2 study period, the clearest reported signal was that most admitted patients did not develop severe clinical disease.

The mortality analysis nevertheless identified subgroups with higher observed risk, particularly patients with chronic kidney failure, elevated D-dimer, lower lymphocyte proportion or lower albumin. These results support closer attention to clinical severity and laboratory abnormalities in hospitalized hypertensive patients, but the study does not establish a preventive or therapeutic regimen.

Subject of Research: Clinical severity and mortality of Omicron BA.2 infection among hospitalized patients with hypertension

Article Title: Clinical epidemiological characteristics of Omicron variant BA.2 infection in patients with hypertension

Article References: Qian, W., Hu, Q., & Zhang, T. (2026). Clinical epidemiological characteristics of Omicron variant BA.2 infection in patients with hypertension. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14288-1

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14288-1

Keywords: Omicron BA.2, SARS-CoV-2, hypertension, COVID-19 severity, patient mortality, retrospective cohort, chronic kidney failure, hs-CRP, D-dimer, albumin, lymphocyte count, Clinical