While a few have already hit the market, there are still dozens of coronavirus vaccines in development around the globe.
Some use tried-and-true technologies, other use novel approaches. The shots were all tested differently, and some were allowed to go into use even before they were rigorously tested. How well they work varies, with preliminary study results ranging from 50% effective to over 90%.
So far, regulators in different countries have allowed use of about a half dozen, mostly under emergency use provisions. A few more are getting close. The ones available now all require two doses, given weeks apart.