Sharon Stone has condemned “non-mask wearers” for the fate of her younger sister, who is hospitalised with coronavirus and “fighting for her life”.

The actor, 62, shared photographs on Instagram of the equipment in her sister’s room, as well as a medical worker in full PPE. She wrote in the caption: “My sister Kelly, who already has lupus, now has Covid-19. This is her hospital room. One of the Non-Mask wearers did this,” Stone wrote.

“She does not have an immune system. The only place she went was the pharmacy.”

Stone added: “Can YOU FACE THIS ROOM ALONE? Wear a mask! For yourself and others. Please.”

In an Instagram video, Stone expanded on her sister’s condition, saying that Kelly’s husband, Bruce Singer, is also “fighting for his life” in a coronavirus ward.

The family live in Montana, where testing is confined only to those with symptoms. Stone said her mother, who has had two heart attacks, five stents and a pacemaker fitted since lockdown, has been unable to get tested.

Stone said she had tried unsuccessfully to contact the governor of Montana and the health department.

“My grandmother died of Covid and my godmother died of Covid,” said Stone. “My sister and her husband are fighting for their lives and my sister is not doing well.”

Stone ended her video by urging viewers to vote, expressing support for Joe Biden and Kamala Harris in their campaign for the US presidency.

Last week, Stone spoke publicly about three of her own near-death experiences. As well as the stroke she suffered in 2001, leading to a two-year break from acting, she said a clothesline came within “a 16th of an inch from my jugular vein” when she was 14. In addition, she was hit by lightning as a child, conducted through water after the family well was struck. “I got picked up and thrown across the kitchen and hit the refrigerator. Thankfully, my mum belted me round the face and brought me to.”