Now it would seem (in this period the conditional is always a must) that every charter on Zanzibar and consequently also on Kenya is closed.
The Blu Panorama flight departed tonight, Monday, March 9, does not carry passengers and comes to the two tourist destinations of the Indian Ocean, Mombasa and Zanzibar, completely empty and ready only to welcome the Italians who must return home. It is not yet certain that this is the last one, but in case of cancellation of flights in the next two weeks, customers will have refunds but a certain difficulty to be re-routed on other flights.
The communiqué from the Tanzanian Autonomous Region of the island of Zanzibar arrived a short while ago and is signed by Mahmood Thabit Kombo, Zanzibar's Minister of Information, Tourism and Culture, explaining that, given the emergency and the continuing growth in the number of forty people in Italy, it is announced that Italian passengers on all direct flights from Italy will be banned from disembarking immediately.
Only completely empty flights will be accepted in order to allow the companies to take their compatriots back to their Motherland. Consequently, even flights to Mombasa, which, as explained in recent days, depend on the route to Zanzibar, will not bring any tourists of those scheduled to depart and then arrive tomorrow in some resorts in Watamu and Malindi.
The Farnesina's Viaggiare Sicuri website also confirms this: 
"In order to prevent the spread of the COVID-19 (new coronavirus), the government of Tanzania and the semi-autonomous government of Zanzibar have ordered checks on all passengers arriving at international airports and the port of Zanzibar. All people showing suspicious symptoms are tested for the coronavirus and if positive they can be placed in quarantine. The local authorities announced on 9 March, with immediate effect, the termination of all charter flights from Italy to Zanzibar. It is recommended to check the status of the flight with your airline before travelling to the airport. Turkey has ordered the suspension of air traffic with Italy. If you have purchased a ticket to/from Tanzania with a stopover at the airports in Turkey, you should check with your airline directly with the airline to ensure that the flight is in good condition and that you are able to board. Other airlines could reduce the frequency of air connections between Italy and Tanzania. It is recommended to check the operation of your flight with the airline of reference, before going to the airport.
In this sense the season of so-called mass tourism, or package holidays, is officially closed. 
And frankly, it's better that way.