Do I need to ready my Shield spell to use it as a reaction later?

@JeremyECrawford Just started DnD 5e. Do I need to ready my Shield spell to use it as a reaction later in the round?

— Vanilla Gorilla (@TheVnlaGorilla) August 24, 2016

If an effect, like the shield spell or an opportunity attack, lets you use your reaction, you don't Ready it. #DnD https://t.co/zYMUxIclHW

— Jeremy Crawford (@JeremyECrawford) August 24, 2016

@TheVnlaGorilla @JeremyECrawford nope. You only need to ready things that are not normally used as reactions. #wotc staff

— (((Mike Mearls))) (@mikemearls) August 24, 2016