JN. 1, a highly contagious off-shoot of the Omicron strain, now makes up around 86 percent of COVID cases in the United States after accounting for less than 5 percent of infections nationally in early November, the Centers for Disease Control and Prevention (CDC) reports. It's also the most dominant across the globe. JN.1 cases in the US have doubled over the last month. In late December, it caused 44 percent of cases in the US, after making up around 22 percent of infections in the middle of December. That's around the time the World Health Organization (WHO) declared JN.1...