WASHINGTON, May 15 -- Sen. Roger Marshall, R-Kansas, issued the following commentary to the FoxNews.com: * * * U.S. Senator Roger Marshall, M.D. penned an op-ed for FOX News about the importance of getting to the bottom of the origins of COVID-19. The Senator said in part, "In approximately two weeks, the U.S. will be represented at the World Health Assembly where we need to ally with all nations and fight for a full and unrestricted investigation of the origin of COVID-19. We must demand full  more