There is now a new list of rules of entry to the Czech Republic just released.

Everybody entering the Czech Republic will now have to fill in the Passenger Locator form regardless of where you are coming from. https://plf.uzis.cz/

From all Green and Orange Zone (Low to Medium Risk) countries if you are an EU/EU+ citizen you have to have an Antigen or PCR test (Antigen within 48 hrs of arrival, PCR within 72 hours) either before or after you travel into Prague unless you have been fully vaccinated and 14 days after the second dose and have your certificate to show it. If vaccinated then no testing is needed.

From all Green and Orange Zone (Low to Medium Risk) countries if you are non EU then you have to have either an Antigen or PCR test (Antigen within 48 hrs of arrival, PCR within 72 hours) before or after your arrival., unless you have been fully vaccinated with an EMA approved vaccine in the EU/EU+ and have the certificate to prove it. You must bring your invitation letter that I sent to you to show your reason for entering the Czech Republic.

From all Red and Dark Red Zone (High to Very High Risk) countries if you are an EU/EU+ Citizen you have to have a negative PCR test before and another one after arrival after five days of self isolation unless you have been fully vaccinated in the EU/EU+ and it is 14 days after the second dose and you have your certificate to show it. If fully vaccinated on these conditions then no testing is needed. 

From all Red and Dark Red Zone (High to Very High Risk) countries if you a non EU citizen you have to have a negative PCR test before, and another one after arrival after five days of self isolation, unless you have been fully vaccinated in the EU/EU+ with an EMA approved vaccine and have the certificate to prove it. You must bring your invitation letter that I sent to you to show your reason for entering the Czech Republic.

From all Black Zone countries there is a complete entry ban unless Czech.

Rules of entry 9th July 2021 Czech and EU 

Rules on entry 9th July non EU

Map of countries 12th July

Map list of countries by degree of infection risk from 12 07 2021