Raised in Manalapan Township, New Jersey, Andrews attended Manalapan High School, graduating in 2009. As a senior in 2009, he set the U.S. high school indoor records for both the 800 m, at 1:49.21, and the 1000 m, at 2:22.28. At the 2010 World Junior Championships in Athletics in Moncton, Canada, Andrews won a bronze medal over 800 m, becoming (along with silver medalist Casimir Loxsom) the first American male to medal in a middle distance event at the world junior championships.