The Problem With Vaccine Development: "More effective vaccine for African swine fever developed"

It takes time.
Labs around the world have been working on this for a year and only now are they getting close to something that works
From PoAndPo Agrifish:

A vaccine against African swine fever, that appears to be far more effective than previously developed vaccines, has been developed by US Government and academic investigators.
The research appears in the Journal of Virology, a publication of the American Society for Microbiology....

Here's the story at Technology Networks: "Vaccine for African Swine Fever Virus Shows Promise"

And on Coronavirus, STAT January 24:
How fast can biotech come up with a vaccine for the latest outbreak?