www.flypgs.com According to the measures taken by the authorities, passengers that are 6 years and older are required to submit a negative PCR test result done within the last 72 hours prior to their entrance to Turkey before their flights starting from 30.12.2020. Those who don’t submit negative test result will not be accepted to flight.
https://www.turkishairlines.com/As of December 28, 2020, passengers arriving from abroad are required to have taken a PCR test with a negative result within 72 hours prior to their flight, and the test result should be submitted during check-in. Passengers failing to submit a negative PCR test are not allowed to board the flights. This application is valid until March 1, 2021.