Will Omicron Require New Covid Vaccines?

Since the identification of the Omicron variant, vaccine makers - like Pfizer and Moderna - have been racing to figure out if the existing Covid-19 vaccines are effective against it or whether they should develop new, Omicron-targeted vaccines. WSJ's Denise Roland explains what scientists have to consider. Learn more about your ad choices. Visit megaphone.fm/adchoices