Humans and disease-causing organisms have inhabited the earth, I believe for as long as the human race existed, and over time we've managed to survive without getting wiped out, even with the world facing several outbreaks in the past, the most recent being the coronavirus outbreak, and one of the methods that have been devised to protect us is Vaccination against sicknesses and viruses.
From my little knowledge of what a Vaccine is, it is a substance that when administered to the body helps stimulate the body's immune system to protect against a specific disease, this way, when we get infected by the sicknesses in subsequent time, our body activates its immune to help us fight the sickness.
I grew up with different vaccine experiences, especially the polio vaccine, some health workers would usually visit schools and homes to administer these vaccines to kids through their mouths and their thumbnail gets marked with a permanent marker for a while, this is to make sure that they don't get an overdose of the vaccine during the vaccination period, they were the regular ones given to kids, as most of the important ones would have already been given to them as a baby.
It was when I had my first child I learned about types of the vaccines like BCG, Measles, Penta, etc are to be given to babies before they clock one year. My mum commended the awareness of mums of these days according to her, so many children's lives were lost those days to these illnesses that would have been prevented if they had been vaccinated early, but mothers of those days were ignorant and cared less about vaccine not until the mortality rate of infant grew high did they reconsider their ignorance, and indeed the quality of life has improved, it's rare to see children down with polio like it was rampant in the past, and no child had to die of measles anymore.
Vaccines are not restricted to babies alone though, as adults still get vaccinated when the need arises and also as new vaccines are being introduced like the coronavirus vaccine. People had different conflicting thoughts about this vaccine as different conspiracy theories were flying about, some of which included that it would alter our DNA, some said it was a forced 666 mark that was stated in the Bible, and anyone who received it would not make heaven, this was common among some Christians, there was also another that it wasn't a vaccine but a front to install microchips on everyone so we become traceable any day, any time.
I was also skeptical on receiving the vaccine when I heard that it killed someone who received it the previous day, I believe all of these theories are rooted in fears, the best question to ask yourself is would you rather not believe and not get vaccinated it even if you don't believe still get vaccinated. Life is not meant to be played with so it's better for one to get vaccinated as all vaccines we receive wholeheartedly today and even administered to our children were once under trial as well.