VACCINES!
Vaccines prevent terrible diseases that most people have never even heard of. These diseases are not common any more, because they have been prevented by vaccines! However, except for Smallpox, they are not completely gone from the world; and can make a very horrible comeback at any time. Some of the diseases are worse than others. And, yes, vaccines do have side effects. The side effects are similar to the disease, but far less severe. This makes sense, if you think about it.
Some people promoting "do not immunize" are actually making money by promoting "supplements" and other things which have no value and can be harmful. Some of those "influencers" do not realize they are doing this, but many do, and are getting paid to do so. It is best to research the origin of any idea or post that you come upon.
Now, what should you as a parent do? Well, you should put your child's safety first, and get them immunized! Give them acetaminophen for the few hours of fever and achiness that they will experience. But if you have questions or doubts, go and talk to your own pediatrician! Your pediatrician has at least 11 years of intense study and training post high school, in EXACTLY all this stuff, and has years of experience!
Occasional children do have a more severe reaction to a vaccine, typically a febrile seizure. If this has happened to your child, report it to VAERS, and follow recommendations for that vaccine complication in future. Vaccines do not cause autism; this is well proven. That original "study" was done by a fraudster in England, and is well documented.
Now, what is "thimerasol"? Thimerasol is a preservative and it contains a tiny amount of mercury. There is such a thing as mercury poisoning. The poisoning requires huge doses, and may occur in an industrial situation. It does not happen from the trace amounts that are used in certain vaccines. Other preservatives are more expensive, less effective, and can allow contamination, which can be a major problem. If you eat fish, you ingest more mercury than you could ever get from vaccines.
Now, are all the vaccine recommendations 100% for the best? Possibly not. There is much uncertainty in life. One example is the flu shot; it is not always effective in every year, because the virus itself changes. But the bottom line is that these diseases are BAD. I am old enough to remember ALL of the diseases which we now have vaccines for. My father had siblings who died of two of them. Please, if you have concerns, go and talk to your pediatrician! He or she is probably the most knowledgeable and trustworthy person you could ever meet in the world!