Twin brothers and French TV stars Grichka and Igor Bogdanoff have both died of COVID-19.

According to reports from CBS, Igor died on Monday, which came just six days after Grichka died on December 28. The brothers were 72 years old.

The twins’ lawyer, Edouard de Lamaze, told CNN that he learned of his clients’ deaths from their relatives, confirming the news to the outlet.

“They are dead from Covid. They were both at the same hospital, Grichka died six days earlier than Igor,” he told the publication.

According to reports from BBC, the brothers--who were hospitalized in mid-December 2021--had not received the COVID-19 vaccine. But, according to a friend of the Bogdanoff family, the pair weren’t against vaccines.

“People have said they were anti-vaxxers but they absolutely weren’t,” family friend Pierre-Jean Chalençon told French TV station BFMTV, per the BBC.

In December, when he was asked about his vaccination views on a French radio show, Igor cited French scientist Dr. Didier Raoult, who popularized hydroxychloroquine as a COVID-19 treatment. At the time, Igor agreed with Dr. Raoult’s opinion that it was best to wait for future vaccines to be developed rather than receiving the treatment that is currently available.

Grichka and Igor Bogdanoff rose to fame in the late 1970s with their TV show Temps X, which premiered in 1979. The series covered science fiction, and was a hit with viewers due to its simplified approach to scientific topics.

Temps X ran until 1987, according to the BBC. After their show ended, Grichka and Igor went on to write doctoral theses in mathematics and physics, though their work was largely dismissed by academics.

Before they were hospitalized, Grichka and Igor were planning a return to the small screen, BBC reports. The twins had been developing a pilot to reboot Temps X, which they planned to host on a spaceship, once again.