The head of Russia’s human spaceflight program who contracted the coronavirus has died at age 65, the national space agency Roscosmos announced Tuesday.

Yevgeny Mikrin, designer general of the Energia aerospace and defense corporation, died weeks after attending the April 9 launch of a three-man crew aboard a Russian capsule to the International Space Station (ISS). Mikrin’s coronavirus infection was asymptomatic, the state-run TASS news agency reported in mid-April.

“The best doctors fought for his life for several weeks,” Roscosmos chief Dmitry Rogozin said in a statement announcing Mikrin’s death. 

“Unfortunately the illness gained the upper hand,” Rogozin said without specifying the cause of Mikrin’s death.

Russia frequently records different causes of death, including double pneumonia, for patients who test positive for Covid-19. Russia has the lowest official coronavirus death count among the 10 countries with the most cases.

President Vladimir Putin said Mikrin had made an “invaluable” contribution to Russia’s national space program.

Rogozin has previously said that the ISS crew is coronavirus-free because the incubation period for the virus had passed, echoing NASA’s confidence in the astronauts’ pre-launch quarantine.

At least 173 Russian space industry employees have contracted Covid-19 and six have died as of April 30, before Mikrin’s death, Rogozin said

Anatoly Ivanishin and Ivan Vagner of Roscosmos and NASA’s Chris Cassidy were the first new crew members to reach the ISS after the pandemic began. A week later, two astronauts and one cosmonaut returned to Earth for the first time since the World Health Organization declared Covid-19 a global pandemic.