From: Seroprevalence of an antibody against diphtheria, tetanus, and pertussis among the elderly in Khon Kaen, Thailand
Age group (years)
Total
Male
Female
p value†
61–65
104
25
79
0.18
66–70
99
23
76
71–75
92
27
65
76–80
70
43
81+
21
44