When you have a non-connecting flight or long layover in any country with a Plan to Escape the airport to explore the city, you should have a permit to travel through this country to reach your destination. Or in other meaning Transit Visa.
In Turkey, the transit visa is no longer than 72 hours (three days) and can be obtained like a Tourist Entry Visa.
If you are planning to leave the airport and spending a day or more in the cities like Istanbul, Izmir, Cappadocia, Pamukkale, Fethiye, Antalya, Bodrum - while it could be a once-in-a-lifetime opportunity - you should have a transit visa.
Passengers in non-connecting flights should pass through the immigration to collect their luggage and check-in for the next flight, in this case, a Transit visa is required.
But if you are going to connect to another flight without any plan to leave the airport, you don’t have to take the visa.
Been waiting a long time, visiting the Istanbul Airport CIP lounge could be a good idea ... more information about Istanbul airport CIP Lounge.
The transit visa is available for Citizens from more than 100 countries to enter Turkey. You can obtain your visa through the Turkish travel visa online system.
You need a valid passport, credit card, and email address to apply for your single- or multiple-transit visa.
It is straightforward to apply for a Transit visa to Turkey. You can take your visa online for turkey easily during your ease everywhere office, home ... etc.
Applicant should give some details about his name, date, and place of birth and contact details phone numbers and email. It is important to add your passport number correctly and the passport issuing and expiration date.
Before sending the application, we advise the travelers to check out their details. you should pay the official Turkish visa fee with a debit or credit card. The applicant has to provide a valid email address.
You will receive the transit entry Visa for Turkey as soon as the application confirmed from the Turkish government visa system. it takes less than 12 hours to Acquire the visa, therefore, we advise you to apply for the visa at least 24 hours before your journey or your layover in Turkey.
Some nationalities are not eligible to take the electronic visa Turkey online. They have to visit the Turkish embassy to give some papers and information about their journey.
Entering Turkey is easy as always. so there is no need to perform any medical test to enter the Turkish land or even if you are a transit visitor.
It‘s mainly related to your travel destination if you are a transit traveler you can check the countries travel restrictions to get more info.
Anyway if your final destination required any medical test you can do it in the waiting time at Istanbul Airport, Sabiha Gokcen Airport, or Antalya Airport .. more information about medical test in Istanbul Airport from the link