Firefly Health, a Watertown, Mass.-based virtual-first healthcare company, closed a $40M Series B financing round. The round was led by Andreessen Horowitz (a16z) with participation from existing investors F-Prime Capital and Oak HC/FT. As part of the deal, a16z General Partner Julie Yoo will join the Firefly Health board. The company intends to use the funds to expand operations and its business reach.