I believe there is a faction of people that want COVID-19 to kill off a substantial portion of the world's population in developing countries. To achieve that goal, they need to:

1. develop a way to prevent the humanity (most people living in developed countries along with the perpetrators themselves) from becoming extinct

2. get the virus to mutate into a deadly strain

3. ensure that deadly strain somehow gets spread to the general population without killing off the host first

1, 2, and 3 are all done by creating a leaky vaccine. This is well-understood science and we have seen this phenomenon in industrially raised chickens and Marek's disease.

4. restrict access to the jabs in developing countries

5. export the deadly strain(s) into those places

4 is easily explained by "logistic challenges." 5 is done by sending infected tourists.