Is the gut microbiome of vaccinated #s contagious?

My parents both got vaccinated recently and had no side effects but I began to get some of the side effects of the vaccine just from being around them all the time including things like dehydration and chills and muscle soreness and I think I might have had arm pain too. I also heard India’s CoVid cases began to spontaneously decline weeks ago even though less than 1/25 of their population has been vaccinated and nobody knows why the cases went down.