TABLE 5 Estimates of Vaccine Efficacy and 95% CI by Vaccine Received and by Interval of Follow-up Cough and Duration Vaccine Received Interval 1/10/95-31/10/96 (VE % [95% CI]) 1/11/96-31/10/97 (VE % [95% CI]) 1/11/97-31/10/98 (VE % [95% CI]) Total Stage 3 (VE % [95% CI]) Any cough 7 d SB 52 (0-76) 76 (61-86) 76 (66-83) 76 (69-81) CB 62 (16-82) 78 (63-87) 77 (68-83) 78 (72-83)  14 d spasmodic or 21 d any cough SB 62 (16-82) 74 (54-86) 79 (70-85) 78 (71-83) CB 70 (32-86) 78 (61-88) 80 (71-86) 81 (74-85)  21 d spasmodic cough SB 83 (49-93) 87 (65-95) 86 (74-93) 86 (79-91) CB 81 (46-93) 89 (69-96) 86 (74-93) 86 (79-91) VE indicates vaccine efficacy; SB, DTaP SB; CB, DTaP CB.