Tsimikas missed Greece’s Nations League opener with Slovenia on Thursday and will sit out Sunday’s game against Kosovo as well.
On Friday, the Greece Football Federation announced a player had tested positive for covid-19, declining to make his identity known but Tsimikas has been identified as the victim.
An official statement read: "The Greek Football Federation was informed today of a positive COVID-19 sample on the results of checks carried out by the authorised by UEFA medical service among members of the mission of the national men's team, which is located in Ljubljana and preparing for Sunday's match with Kosovo in Pristina.
"UEFA's protocol is being adhered to and EODY [Hellenic National Public Health Organization] as well as the GGA health committee were immediately informed.
"The member of the squad who had a positive sample and was isolated for the last 36 hours for precautionary reasons from the other members of the squad, leaves the team tomorrow morning, while the preparation of the Greek team continues.
"The other members of the squad underwent a new test today in accordance with the UEFA protocol and the results will be announced tomorrow before the departure of the team to Kosovo."
Liverpool signed Tsimikas from Olympiacos for £11.7m last month.
Liverpool will start the 2020/2021 Premier League season with a home game against Leeds United next weekend.
