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COVID-19 and Comorbidities: Introduction

Maryam Shapland, MD
Maryam Shapland, MD
Vice President and Medical Director
RGA U.S. Mortality Markets

Since the December 2019 identification of a novel coronavirus (later named SARS-CoV-2) in Wuhan, China, and characterization of the disease known as COVID-19 in the early months of 2020, there has been a substantial body of literature detailing the effect of age and chronic conditions on disease severity and mortality.  One of the earliest studies2 of the clinical features of novel coronavirus cases in Wuhan prospectively collected and analyzed the data on 41 patients with laboratory-confirmed infection who were admitted from December 16, 2019 to Jan 2, 2020. The median age of these patients was 49 years. Associated underlying disease included diabetes (20%), hypertension (15%), and cardiovascular disease (15%).

Comorbidities of 1482 US-Hospitalized PatientsAs the virus continued to spread, it became more evident that the elderly and those with underlying comorbidities were more likely to develop critical illness and experience a higher fatality rate. A recent meta-analysis4 revealed that the proportion of underlying diseases were significantly higher in critically ill and fatal cases compared to non-critically ill patients; in particular, having diabetes (OR 3.68), hypertension (OR 2.72), cardiovascular disease (OR 5.19) and respiratory disease (OR 5.15) put patients at high risk for severe disease and mortality. Patients with cancer – particularly those with hematologic, lung and metastatic malignancies – have also been found to be at significant risk of severe outcomes from coronavirus disease, with higher observed death rates (OR 2.34) and higher rates of intensive care unit (ICU) admission (OR 2.84).1 The odds ratio (OR) is a measure of the association of an exposure to an outcome; for example, an odds ratio of 2 doubles the odds of an outcome if there is a particular exposure.

In the US, the CDC has published the Morbidity and Mortality Weekly Report3, which includes the characteristics of patients whose COVID-19 infection was lab-confirmed in March 2020. It is evident from this report that comorbidities play an important role in disease severity, as 89.3% of hospitalized patients have underlying disease.


  1. Dai, M et al. Patients with cancer appear more vulnerable to SARS-COV-2: a multi-center study during the COVID19 outbreak. Cancer Discov April 28 2020 DOI: 10.1158/2159-8290.CD-20-0422
  2. Huang, C et al. Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. Lancet; 395(10223): 497-506, 2020 02 15.
  3. US Department of Health and Human Services/Centers for Disease Control and Prevention. Hospitalization Rates and Characteristics of Patients Hospitalized with Laboratory-Confirmed Coronavirus Disease 2019-COVID-NET, 14 States, March 1-30, 2020. MMWR/April 17, 2020/Vol 68/No 15
  4. Zheng Z, Peng F, Xu B et al. Risk factors of critical and mortal COVID-19 cases: A systematic literature review and meta-analysis. Journal of Infection (2020), doi: