The incidence of respiratory infection was lower with zinc amino acid chelate ( 1.42 per 1,000 child-days ) compared with placebo ( 3.3 per 1,000 child-days ) ( RR = 0.43 , 95 % CI : 0.196 to 0.950 , p = 0.049 ) and with zinc sulfate ( 1.57 per 1,000 child-days ) ( RR = 0.90 , 95 % CI 0.382 to 2.153 , p = 0.999 ) .