Last week, the U.S. Centers for Disease Control and Prevention (CDC) released new data that shows how many Americans have died of COVID-19 due to underlying, contributing medical conditions.

The report revealed that 94% of patients who died of coronavirus also had other “health conditions and contributing causes,” while the remaining 6% of deaths had COVID-19 as the only cause.

The CDC report read, “Table 3 shows the types of health conditions and contributing causes mentioned in conjunction with deaths involving coronavirus disease 2019 (COVID-19).”

“For 6% of the deaths, COVID-19 was the only cause mentioned.” It added. “For deaths with conditions or causes in addition to COVID-19, on average, there were 2.6 additional conditions or causes per death.”

The CDC listed the top underlying medical conditions associated with COVID-19 deaths, including influenza and pneumonia, respiratory failure, diabetes, hypertension, vascular and unspecified dementia, cardiac arrest, heart failure, renal failure, intentional and unintentional injury, poisoning, and other medical conditions.

Globally, the virus has affected more than 25 million people, with the U.S. leading the count. American public health officials have reported more than 6 million COVID-19 cases, with over 187,000 deaths so far.

The CDC explained that their data uses provisional death counts to “deliver the most complete and accurate picture of lives lost to COVID-19.”

The number of deaths is based on death certificates, which the CDC said are the most reliable source of data. A death certificate typically contains information that is not available anywhere else and includes the cause of death, comorbid conditions, race, ethnicity, and place of death.

The CDC noted that provisional death counts might not match counts from other sources like numbers from county health departments. That’s because death certificates take time to be completed. Also, states report at different rates and it takes officials extra time to code COVID-19 deaths.

Furthermore, some reporting systems use different definitions or methods for counting deaths. The CDC explained, “Provisional data is not yet complete, provisional counts are not final and are subject to change, and that death counts should not be compared across states.”