Nearly 170 million people have been vaccinated against Covid-19 in the United States -- which means the same amount have been handed a version of the Centers for Disease Control and Prevention's white record card.

The CDC's vaccination card is likely to be the primary proof of vaccination going forward as the US continues loosening pandemic restrictions. Much of the information on the card is straightforward, but other parts, such as the vaccine lot number, point to key details that…

A new kind of COVID-19 vaccine could be available as soon as this summer.

It's what's known as a protein subunit vaccine. It works somewhat differently from the current crop of vaccines authorized for use in the U.S. but is based on a well-understood technology and doesn't require special refrigeration.

In general, vaccines work by showing people's immune systems something that looks like the virus but really isn't. Consider it an advance warning; if the real virus ever turns…