has to do with being a responsible member of a community...COVID-19 is a communicable disease that depends on close contacts among the human population in order to replicate and spread...meanwhile killing a significant number (561,000+) of those hosts...therefore, it is incumbent upon ALL community members to take proven steps to eliminate this threat to the general welfare. The best and most effective step in this case is to get vaccinated with one of the most effective drugs yet produced as soon as it becomes available.
To understand this situation and not take the vaccine when presented indicates one of two characteristics...a) a genuine fear (not unreasonable) of a new drug and what it might do to one's health, which is understandable and a key reason why it is not mandatory...or b) a willful disregard for the welfare of others...for whatever reason they may have...which undeniably works against the best interest of the community.
Hopefully that helps you understand...if not, there are more megabytes still available.