What are you on about? Of course, there are multiple cases of people being reinfected. There was the case in the US when he got 2 negative tests and got released, to only get infected 3 months later and suffer worse. At the beginning, we thought that might be just mistaken on tests from South Korea, but it is clear that is not the case now that we know more about the virus.
And there is no biomedical knowledge that says that you cannot get reinfected from the same virus. In fact, more often than not you can. Like from flu. Or from the common cold (some of which are caused from coronaviruses, so close to this disease). Or from yellow fever. In fact, even from measles (which generates an extreme immune response) while highly unlikely, you can still get reinfected. From coronaviruses, the question is not if you can get reinfected, but when you can get reinfected. The hope was that it cannot be for 1-3 years (MERS and SARS), but it seems that it can be much shorter than that. Because people can get reinfected with the same disease, they get revaccinated for some (flu for example) or get vaccine boosters later.
Which makes herd immunity the most ridiculous idea since Trump wanted to nuke a hurricane.
That study showed that primates getting the vaccine were generating 3 times as many antibodies than those who got the disease. Additionally, modern vaccines do not mimic the virus, they instead give information on how to fight the virus (though these types of vaccines have not been successful yet, but that is what Moderna and co. are trying). People are not gonna get weakened/dead versions of the virus int heir bodies.