Where are you getting this number from? Any numbers coming from the Cuban government have to be treated as unreliable, as it is common practice to restrict doctors from what can be reported, unless they want to lose their license.
> Cuba’s reaction to the coronavirus threat was swift. A “prevention and control” plan, prepared in January 2020, included training medical staff, preparing medical and quarantine facilities, and informing the public (including tourism workers) about symptoms and precautions. So, when the first three reported cases were confirmed on March 11, arrangements were in place to trace and isolate contacts, mobilise medical students for nationwide door-to-door surveys to identify vulnerable people and check for symptoms, and roll out a testing programme.
[1] https://theconversation.com/coronavirus-response-why-cuba-is...
Governments with the same governance structure as Cuba (Vietnam, China) have been achieving even better numbers, despite lifting all measures and being full of foreigners. Because of this I expect actual evidence the data is false.