All viruses have a very high mutation rate. It is very possible for a mutated virus not to be affected by immunity against a previous form of the virus. So every time a new strain of Covid-19 appears, there is a question of whether the existing vaccines will protect against it.
This “oscillation” of the vaccine news occurs because of the nature of viruses and immunity. It can take years to develop a vaccine, but viruses can mutate during the course of a single infection.
I agree, that is a fact. That does not mean that misinformation and DIS information will not be promulgated in an effort to keep the population cowed.