Video above: Experts say flu shot very important in COVID yearDr. Umair Shah remembers the last mass vaccination campaign the U.S. waged.It was in 2009, when the H1N1 “swine” flu broke out in April, right at the end of the regular flu season.”That was very challenging,” Shah, who heads the Harris County, Texas, health department, told CNN.”There were a lot of moving pieces. It took