Seattle to Shanghai China $447 RT on Delta Airlines Travel Feb-May NONSTOP

Delta Airlines have roundtrip airfares from Seattle (SEA) to Shanghai China (PVG) for $447 including taxes/fees. This is nonstop service.
Travel availability:
Departs SEA: good amount of dates beginning Feb 16 thru May 4
Returns SEA: good amount of dates thru May 15
Book this on Priceline .
Airline website.
My sample travel dates: March 1-8, 2017