By Ahmed Aboulenein and Julie Steenhuysen WASHINGTON (Reuters) -President Joe Biden on Tuesday announced a national action plan to be developed by the U.S. health department to tackle the looming health crisis of long COVID, a complex, multi-symptom condition that leaves many of its sufferers unable to work. Long COVID, which arises months after a COVID-19 infection, affects nearly 7% of all U.S. adults and 2.3% of the overall population and has cost an estimated $386 billion in lost wages, savings and medical bills, according to an analysis by the Solve Long Covid Initiative, a non-profit res…