Table 6.

DTaP and DTP Vaccine Efficacy Against Cough Illnesses Analyzed by Various Definitions for Primary Cases, Secondary Cases, and Noncases and the Exclusion of Noncases Who Received Macrolide Antibiotics or Trimethoprim-Sulfamethoxazole During the Exposure Period (7–42 Days)

Case Category*Vaccine Group
Primary
Case
Secondary
Case
NoncaseDTDTPDTaP
Attack Rate, %
(no. cases/
no total)
Attack Rate, %
(no. cases/
no. total)
Vaccine
Efficacy, %
(95% CI)
Attack Rate, %
(no. cases/
no. total)
Vaccine
Efficacy, %
(95% CI)
a. Cough illness ≥7 days duration with laboratory confirmation
Ancillary IAncillary IPrincipal66 (19/29)19 (12/62)70 (48–83)32 (18/56)51 (22–69)
Ancillary II70 (19/27)26 (12/46)63 (36–78)41 (18/44)42 (11–62)
 7%26%21%
Ancillary IIIAncillary IPrincipal47 (34/72)13 (21/167)73 (57–83)20 (31/158)58 (38–72)
Ancillary II57 (34/60)19 (21/113)69 (51–80)27 (31/116)53 (31–68)
17%32%27%
b. Typical pertussis with laboratory confirmation
Ancillary IAncillary IIPrincipal56 (14/25)3 (2/61)94 (77–99)9 (5/54)84 (61–93)
Ancillary II64 (14/22)6 (2/36)91 (66–98)16 (5/31)75 (42–89)
12%41%43%
Ancillary IAncillary IIIPrincipal58 (15/26)3 (2/61)94 (77–99)9 (5/54)84 (61–93)
Ancillary II65 (15/23)5 (2/36)91 (66–98)15 (5/31)75 (42–89)
12%41%43%
c. Any cough illness
PrincipalAncillary IVPrincipal81 (21/26)37 (20/54)54 (32–69)50 (23/46)38 (13–56)
Ancillary II81 (21/26)40 (20/50)50 (27–66)56 (23/41)31 (3–50)
0%7%11%
Ancillary IIIAncillary IVPrincipal65 (53/82)40 (70/176)38 (22–52)41 (69/167)36 (19–50)
Ancillary II67 (53/79)43 (70/162)36 (19–49)45 (69/154)33 (16–47)
4%8%8%
  • Abbreviations: DT, diphtheria and tetanus toxoids vaccine; DTP, diphtheria-tetanus toxoids, whole cell pertussis vaccine, adsorbed; DTaP, diphtheria-tetanus toxoids, acellular pertussis vaccine, adsorbed.

  • * See Tables 1 and 2.

  • Percent of exposed subjects with cough illnesses not meeting the secondary case definition.