Omicron is spreading 'every place at once,' experts say. The COVID-19 omicron variant. CAMBRIDGE, Mass. — The omicron variant of COVID-19 is moving faster than surveillance systems can track it and has so unnerved some medical experts they're starting to put the brakes on preparations for their holiday gatherings. "Personally, I'm reevaluating plans for the holidays," Bronwyn MacInnis, director of pathogen genomic surveillance at the Broad Institute of MIT and Harvard University, said on a call with reporters Tuesday. "It's the responsible thing to do and what feels right given the risk." She and a handful of other Massachusetts-based researchers on the call said they've been stunned by the pace by which omicron has been crowding out other variants and taking over the pandemic. The Centers for Disease Control and Prevention reports that about 3% of current COVID-19 cases in the U.S. are omicron. But MacInnis said she thinks that number w...