Warren said her older brother had a career in the US Air Force and spent about five and a half years serving in combat in the Vietnam War, adding that he was charming and funny and a natural leader with a smile that "always seemed to generate its own light, one that lit up everyone around him".
She said it is difficult knowing her brother died alone at the hospital with no family at his side and with no funeral for his family and friends to mourn together.
As of Thursday, the United States has confirmed 800,926 COVID-19 cases and 40,073 deaths caused by the disease, according to a tally from the World Health Organisation, updated at 6:00 pm CEST.
