Every year, millions of people safely receive vaccinations. All FDA-approved vaccines undergo comprehensive and laborious trials prior to being given to the public. Testing during the development process includes screenings to analyze which antigen should be utilized to solicit a response from our immune systems.
The stage that precedes clinical testing is conducted without testing on humans. An exploratory vaccine is initially used in animals to gauge its efficacy and ability to prevent illness. If the vaccine sparks a response from the immune system, then it can be investigated in human clinical trials; this typically takes place over three phases.