There will be no mandatory quarantine for foreign tourists who, as of August 1, 2020, will travel to Kenya on holiday or business, unless they have a fever or obvious symptoms leading to Covid-19 on arrival, while presenting a regular Covid-19 Free certificate which will still be required on departure from their country.
This is one of the crucial points of the new transport protocol presented a few hours ago by the Kenyan Ministry of Transport.
To improve security measures and curb the spread of Covid-19, Minister of Transport James Macharia also announced that the presence at the country's airports will be limited only to workers and travelers, except in cases where travelers need special assistance. 
"The new protocol also includes measures to minimize contact between the crew and passengers at the airport terminal, and to limit physical contact between security officers and passengers, and between airport staff and baggage," Macharia said. "Air operators will also reduce onboard service to the bare minimum and introduce gradual boarding and disembarkation procedures to eliminate crowded passageways.
Another important decision, for those who will have to leave or arrive in the evening, during curfew times, there will be the possibility to be transported by taxi or by a regularly registered transfer, provided they show their boarding pass or air ticket.
For other specifications, we refer you to the official press release and other updates on the portal of Italians in Kenya.