The Covid-19 vaccine developed by Johnson & Johnson began distribution this week, just as new variants of the virus are gaining ground. | Timothy D. Easley/Getty Images

Covid-19 vaccines are here. So are new mutations. Here’s what you should know.

The world is now locked in an arms race with Covid-19, as multiple effective vaccines are being deployed (at staggeringly different rates) around the world. At the same time, new variants of the SARS-CoV-2 virus have been rapidly spreading.

The Covid-19 vaccines that are being distributed in the US, as well as the newly authorized Johnson & Johnson vaccine, have been shown to almost eliminate deaths and hospitalizations from the disease, even for people infected with the new mutations. For a disease that has infected more than 114 million people around the world in just over a year, this is