Carey replaces Harris in Australia Women's WT20 squad
Australia's team doctor Leanne Hutchison said: "Grace has been diagnosed with deep vein thrombosis and started treatment for the condition. After consultation with external specialists and the medical team at Cricket Australia, the decision was made that it was not medically safe for her to fly and play whilst undergoing treatment."
Carey, whose recent match-time includes 16 wickets at 21.50 for Sydney Thunder Women in the Big Bash League, will join the squad on Saturday, ahead of Australia's warm-up match against West Indies in Chennai on Monday.
Carey had received a last-minute call-up to Australia's squad during the last World T20 as well, when Sarah Coyte fell ill, but she did not get a game.