The ARI rate regarding age group Age group (month) Number (n) Number of ARI (n) Percentage (%) p 0-< 12 13 2 15.4 0.007 12-<24 92 22 23.9 24-<36 107 39 36.4 36-<48 111 50 45.0 48-<60 83 36 43.4 Tổng số 406 149 36.7 Remarks: Age group 36-<48 m affected the highest rate 45.0% then age group 48-<60 m 43.4%.