There seem to be some scientists saying and even showing that the vaccine can reduce innate immunity https://www.medrxiv.org/content/10.1101/2021.05.03.21256520v1 and cause negative efficacy

https://www.medrxiv.org/content/10.1101/2021.12.20.21267966v3.full.pdf; thereby potentially acting as a drug whereby the more you have, the more you need.