Vaccines are thoroughly tested in safety and efficacy studies. The requirements for licensing vaccines for market are just as stringent as for any other drug. Most first world countries require the vaccine to be tested in that country before they will give regulatory approval for marketing in that country. Other countries will grant approval following approval in the US or EU.
I suggest checking the medical literature on PubMed, which is where all peer-reviewed scientific papers are catalogued. You can easily find original studies on any vaccine you want--which include details as to whether the study described is pre-clinical or clinical, and if clinical, which phase (1, 2, 3, or 4). Anything you find in PubMed is a past study. If you are interested in current studies, you can check www.clinicaltrials.gov. Most clinical trials conducted anywhere in the world are registered here. So, if you are curious about a candidate vaccine in development, you can look it up.
FYI, a pre-clinical trial includes any experimentation that occurs prior to human testing. A phase 1 trial is conducted with a small number of participants--usually fewer than 100--and is merely a test run to see if the drug is safe, and what the upper limit is for a safe dose. A phase 2 trial is designed to determine an optimal dose of the drug, and is conducted on a few hundred people. A phase 3 trial is an efficacy trial, and usually involves thousands of participants. Not only are these studies "double-blinded", etc., but multiple methods are used to ascertain the efficacy of the vaccine. A phase 4 study is conducted after regulatory approval, and exists to catch rare but significant issues that sometimes are not caught during pre-regulatory studies due to their rarity.
“Vaccines are thoroughly tested in safety and efficacy studies. The requirements for licensing vaccines for market are just as stringent as for any other drug.”
If you have a link to a double blind vaccine study with a placebo (and not another vaccine) as control, I would be happy to look at it. Are there any long term studies of health outcomes between vaccinated vs. unvaccinated children?
With respect to being as stringent as licensing other drugs, such as Vioxx, that is (at minimum) a very troubling thought.
Fortunately most states still have conscience exemptions.