Antenatal tetanus, diphtheria, and acellular pertussis (Tdap) immunization and risk of serogroup 19 IPD in children: An indirect cohort study

Figures & data

Figure 1. Flowchart describing cases and controls included in the study.

IPD, invasive pneumococcal disease; NV/NRT, non-vaccine/non-vaccine-related serotypes; Tdap, tetanus, diphtheria, and acellular pertussis vaccine.

Of the 254 IPD cases identified, 134 were eligible. Among them, 7 individuals were excluded (three had parents who received their Tdap <2 years preceding their pregnancy and for four persons, we were unable to ascertain maternal vaccination status). Of the 127 IPD patients, 37 were considered cases: four serotype 19F and thirty-three serotype 19A IPD.

Table 1. Summary of sociodemographic variables collected for all IPD patients.

Characteristics	Cases (N = 37)	Controls (N = 90)	Total (N = 127)
Exposure to Antenatal Vaccination
Yes	22 (59.5%)	49 (54.4%)	71 (55.9%)
No	15 (40.5%)	41 (45.6%)	56 (44.1%)
Age Category
<1 year	21 (56.8%)	31 (34.4%)	52 (40.9%)
12–23 months	4 (10.8%)	41 (45.6%)	45 (35.4%)
≥2 years	12 (32.4%)	18 (20.0%)	30 (23.6%)
Year of Diagnosis
2018	0 (0.0%)	1 (1.1%)	1 (0.8%)
2019	1 (2.7%)	13 (14.4%)	14 (11.0%)
2020	5 (13.5%)	19 (21.1%)	24 (18.9%)
2021	14 (37.8%)	26 (28.9%)	40 (31.5%)
2022	13 (35.1%)	22 (24.4%)	35 (27.6%)
2023	4 (10.8%)	9 (10.0%)	13 (10.2%)
Vaccine Schedule
Mixed	3 (8.1%)	36 (40.0%)	39 (30.7%)
Only PCV10	33 (89.2%)	49 (54.4%)	82 (64.6%)
Only PCV13	1 (2.7%)	5 (5.6%)	6 (4.7%)
Total PCV Doses Received
1	6 (16.2%)	5 (5.6%)	11 (8.7%)
2	21 (56.8%)	30 (33.3%)	51 (40.2%)
3	10 (27.0%)	52 (57.8%)	62 (48.8%)
4	0 (0.0%)	3 (3.3%)	3 (2.4%)

Data availability statement

Due to the nature of the research and to ethnical and legal restrictions, supporting data is not available.