TABLE 4
Stage 3 Incidence of Laboratory-Confirmed Pertussis by Vaccine Received, by Duration and Type of Cough, and by Interval of Follow-Up*

Cough and
Duration
Vaccine
Receiveddagger
Interval
1/10/95-31/10/96
1/11/96-31/10/97
1/11/97-31/10/98
Total Stage 3 
Cases Rate* Cases Rate* Cases Rate* Cases Rate*

Any cough >= 7 d SB 38 0.89 31 0.84 69 2.13 138 1.24
CB 30 0.70 29 0.78 67 2.06 126 1.12
DT 11 1.87 35 3.57 81 8.92 127 5.12
 >= 14 d spasmodic or
>= 21 d any cough
SB 30 0.70 26 0.70 59 1.83 115 1.03
CB 24 0.56 22 0.59 57 1.75 103 0.92
DT 11 1.87 27 2.75 79 8.70 117 4.72
 >= 21 d spasmodic cough SB 10 0.24 7 0.19 16 0.50 33 0.30
CB 11 0.26 6 0.16 16 0.49 33 0.29
DT 8 1.36 14 1.43 14 1.43 54 2.18

*  Rates per 100 person-years of observation. Notification rates of pertussis for the corresponding birth cohorts and geographical areas in the general population per 1000 inhabitants were 8.9 in 1996, 6.5 in 1997, and 14.8 in 1998.
dagger  SB indicates DTaP SB; CB, DTaP CB.