Actress Sharon Stone shared her sister's experience with Covid-19 on Instagram.
She said people who don't wear masks are to blame, according to reports at CNN.
Stone's post comes as more than 5.4 million people have been infected and 170,052 have died.
Health officials have expressed concern that as the pandemic drags on.
Some Americans are becoming complacent with health precautions and allowing for more spread.
Stone's sister, Kelly, had lupus before being diagnosed with Covid-19, which makes her compromised.
