Before they died, Dr Appleby says they uttered heartbreaking words:
"Just before the patient died, they looked at their nurse and said 'I think I made a mistake, I thought this was a hoax, but it's not,'" Appleby said.
The doctor decided to make details of this case public as coronavirus cases continue to climb in the area.
Appleby wants people - especially younger people - to understand the seriousness of the disease.
"It doesn't discriminate and none of us are invincible," she said.
"I don't want to be an alarmist, and we're just trying to share some real-world examples to help our community realise that this virus is very serious and can spread easily."
The city of San Antonio alone reported nearly 18,000 cases by Thursday night.