Rob, I don't mean to start a fight about this, but you're mistaken about vaccines in general and the COVID-19 ones in particular. Before vaccines are approved, the clinical studies assess the effectiveness (aka efficacy) as well as the safety; few if any vaccines are 100% effective. Smallpox vaccine, the gold standard for vaccine effectiveness, is 95%; measles is 93% for one dose and 97% for two. Vaccines work in two ways, the prophylactic effect (preventing disease symptoms by stimulating the immune system's production of antibodies), and the therapeutic effect (reducing disease symptoms by preparing the immune system to produce T cells rapidly upon infection). During the clinical trials, the effectiveness of the various COVID-19 contenders was widely reported, and you can look that up. One dose of J&J was more effective than one dose of Moderna or Pfizer, which is why the standard for the latter two was set at two doses to start with. Also, most vaccines (and the body's own immune responses) are not forever, partly because of our own immune systems and partly because antigens vary and evolve. For example, once you've had chickenpox, you are nominally immune to it, but the chickenpox virus remains in your system and can express itself later in life as shingles, which is why the older population is encouraged to get a shingles vaccine to bump up the immune response to it for 4 years.