Diabetes, heart disease and long-term lung problems are the most common underlying conditions among Americans hospitalized with the illness caused by the new coronavirus, but more than one in five people requiring intensive care had no such health issues, according to a report issued on Tuesday.
The findings show that higher percentages of COVID-19 patients with underlying conditions were being admitted to hospitals and intensive care units (ICUs), according to the US Centers for Disease Control and Prevention's (CDC) Morbidity and Mortality Weekly Report.
That echoes patterns seen in other countries hit hard by the pandemic.
Preliminary data from 7,162 COVID-19 patients for whom the CDC had complete information show that 37.6% had one or more underlying health condition.
Widespread testing to identify the full extent of the US outbreak has not been available.
Most people infected with the coronavirus develop mild but persistent symptoms such as fever or cough.
But difficulty breathing is a symptom sending many people to the hospital, and the new data show how underlying health conditions heighten the odds of complications requiring hospitalization.
Researchers found that 78% of ICU patients with COVID-19 had at least one underlying health problem, including diabetes (seen in 32% of patients), cardiovascular disease (29%) and chronic lung disease (21%). Twelve per cent had long-term kidney disease and 9% had a weakened immune system.
Among hospitalized patients who were not sick enough to need intensive care, 71% had at least one underlying condition, the CDC analysis found. In contrast, among people with COVID-19 who did not need to be hospitalized, only 27% had one or more long-term health issues.
But being free of chronic conditions offers no guarantees against serious illness as 22% of COVID-19 patients who ended up in an ICU had no history of underlying health problems.
It is not yet known whether the severity or level of control of underlying health conditions affects the risk for severe disease associated with COVID-19, according to the report by the CDC's COVID-19 Response Team.
Many of these underlying health conditions are common in the United States with an estimated 10.1% of US adults diagnosed with diabetes, 10.6% with heart disease, and 5.9% with chronic obstructive pulmonary disease (COPD), along with 7.9% of people of all ages who suffer from asthma.