A new sub-variant of the omicron variant of COVID-19, known as XBB.1.5, is sweeping across the U.S. and parts of China. Here is what you need to know about the new strain. What is the XBB.1.5. sub-variant of COVID-19? The XBB.1.5. sub-variant of COVID-19 is a newer version of the omicron variant that is the virus’s dominant strain, according to the Centers for Disease Control and Prevention (CDC). The variant is considered more transmissible than its earlier counterparts because it can attach itself to cells better. Where is the XBB.1.5. sub-variant of COVID-19 spreading? The XBB.1.5. variant …