Improvement due to the seasons isn't simply due to the physiology of the virus itself. People spend less inside and in confined spaces where its easier to contaminate each other. Additionally, the flu does have significant seasonality, and flu season will be tapering off in the coming weeks and months, meaning more healthcare resources to dedicate to coronavirus infections.

It mostly spread through travel, a lot of it business travel. Little spread in less developed countries are likely because of less travel activity.