A variant of SARS-CoV-2 is now spreading that is much like Omicron, though possibly even more contagious. Omicron, aka “BA.1,” has a sister, “BA.2,” which has the same ancestor strain but has about 20 different mutations. Most of them are outside of the areas that are important for immune recognition — meaning that whatever vaccines or therapeutics work against Omicron will likely work against its sister. BA.2 has presently been found in more than half of the United States.