Since the emergence of new COVID-19 variants, experts have worried that the virus may have developed mutations allowing it to outmaneuver existing vaccines.

Early laboratory studies proved worrisome, showing vaccines seemed to produce far fewer virus-fighting antibodies against some of the newer variants. But real-world experience didn't match those concerns -- people seemed to develop good protection, even when exposed to new variants.

Now, after months of research, vaccine experts across the globe are learning that vaccines still mostly work -- even when those antibodies fail to show up in great numbers -- thanks to other crucial parts of the body's immune system.