First one of these I've seen...
RIA Novosti reports: "Roscosmos State Corporation is convening a meeting on the composition of the crew leaving for the ISS, which means that there may be replacements in the previously announced composition"
Details: "Nikolai Tikhonov was injured, which could become an obstacle to his flight to the ISS. The possibility of replacing him in the crew with cosmonaut Sergei Ryzhikov is being considered"
And more: "The flight of Nikolai Tikhonov, tentatively, may take place in the fall of 2020"
Roscosmos plans to replace the crew of the next expedition to the International Space StationNikolai Tikhonov and Andrei Babkin will not be able to go into orbit for medical reasons. They will be replaced by understudies - Anatoly Ivanishin and Ivan Wagner, the state corporation told RIA Novosti. Launch dates do not change; launch is scheduled for April 9th.
The Russian members of the main crew of the Soyuz MS-16 manned spacecraft, Roscosmos cosmonauts Nikolai Tikhonov and Andrei Babkin, will be replaced by backups for medical reasons.The positions of the commander and flight engineer of the Soyuz MS-16 spacecraft will now be taken by the cosmonauts of Roscosmos Anatoly Ivanishin and Ivan Wagner. The changes will affect only the Russian part of the crew, NASA astronaut Chris Cassidy continues to prepare for the flight in accordance with the established plan.The launch of the Soyuz-2.1a launch vehicle with the Soyuz MS-16 manned spacecraft and members of the long-term expedition ISS-63 is scheduled for April 9 this year from launch pad No. 31 of the Baikonur Cosmodrome.
New understudies, specified Krikalev, most likely, Babkin and Ryzhikov will be appointed. According to him, the further possibility of the flight of the main crew "will depend on medical evidence."
According to a Vedomosti source involved in the ISS program, the crew was replaced due to an eye injury that the commander received while accidentally stumbling into a branch while walking.
https://www.vedomosti.ru/politics/news/2020/02/19/823432-roskosmos-zamenit-ekipazh-ekspeditsii-k-mksGoogle translation:QuoteAccording to a Vedomosti source involved in the ISS program, the crew was replaced due to an eye injury that the commander received while accidentally stumbling into a branch while walking.
By the decision of the MMC on March 14, 2017, Skvortsov was recognized as temporarily unsuitable for health reasons as part of the crew. Alexander was injured during a sports activity. March 15, 2017 Skvortsov in the crew was replaced by Shkaplerov.