It cannot be stressed enough, vaccinations prevent diseases which are highly contagious and frequently deadly.
Vaccinations nearly eliminate the chance of being infected with a given disease. The more people that are vaccinated, the less likely the disease can spread. There are many people who cannot be vaccinated because of special health concerns which are particular to them. People without those special health concerns should get vaccinated. If you choose to not vaccine yourself or your children, you are decreasing the effectiveness of vaccinations that others have had.
These diseases are no joke. Measles, for example, killed more than two and a half million people per year worldwide as late as 1980. In the United States, we began vaccinating against measles in 1963. Prior to that time, almost 50,000 people were hospitalized, 1000 people developed encephalitis, and about 500 people died every year. Thanks to increased vaccination, among other things, measles was considered to have been eliminated from the United States in 2000.
Well, measles is on the rise again and that is due to a failure to vaccinate. Recently, almost a thousand students, staff, and faculty at two California universities were quarantined to prevent the spread of a measles outbreak. You can read about it here: https://www.latimes.com/local/lanow/la-me-measles-quarantine-california-university-20190426-story.html
Some choose not to vaccinate because they are concerned about potential injuries. It cannot be understated how rare injuries from vaccines are.
For example, evidence has not yet conclusively shown that the MMR vaccine causes encephalitis, however, a review of claims for encephalitis following MMR vaccination found a clustering of symptoms in less than one for every million vaccines. And no study in the world has found resulting permanent neurological damage after MMR vaccines. Compare that to the likelihood encephalitis if you contract measles without the vaccine. Encephalitis definitely occurs in one in every thousand cases and, of those, fifty percent suffer permanent neurological damage.
The global evidence is clear that vaccinations save lives and prevent disabilities and that, even where vaccine-related injuries are possible, they are much, much rarer, and far less dangerous, than the devastation wrought by the diseases the vaccines are meant to prevent.
Also, for those who do experience the rare vaccine-related injury, there is a "no-fault" program that provides compensation to those injured. It is called the Vaccine Injury Compensation Program or "VICP". If you believe you have been injured by a vaccine, you should contact an attorney experienced with the VICP as soon as possible, as there are time limits on receiving compensation.