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Table 1 Characteristics of the study population and comparison of risk and confounding factors between PCV7- and PCV13-vaccinated infants

From: Influence of the pneumococcal conjugate vaccines on the temporal variation of pneumococcal carriage and the nasal microbiota in healthy infants: a longitudinal analysis of a case–control study

Characteristic PCV7 PCV13 P value
Number of infants, n (%) 20 (48.8%) 21 (51.2%)  
Gender (male), n (%) 10 (50%) 9 (42.9%) 0.76#
Season of birth, n (%)    0.03 #
 Winter 2 (10%) 8 (38.1%)  
 Spring 4 (20%) 8 (38.1%)  
 Summer 7 (35%) 3 (14.3%)  
 Fall 7 (35%) 2 (9.5%)  
aParental education, n (%)    0.51#
 Low 2 (10%) 4 (19.1%)  
 Middle 6 (30%) 8 (38.1%)  
 High 12 (60%) 9 (42.9%)  
bHA nutrition, n (%) 4 (20%) 4 (19.1%) 0.94#
C-section, n (%) 3 (15%) 3 (14.3%) 0.95#
cChildcare, n (%) 5 (25%) 5 (23.8%) 0.93#
Smoking during pregnancy, n (%) 2 (10%) 1 (4.8%) 0.52#
dSmoking exposure in the 1st year, n (%) 2 (10%) 5 (23.8%) 0.24#
eMaternal atopy, n (%) 6 (30%) 4 (19.1%) 0.41#
Siblings, n (%)    0.18#
 0 3 (15%) 5 (23.8%)  
 1 9 (45%) 13 (61.9%)  
 ≥2 8 (40%) 3 (14.3%)  
Gestational age at birth [weeks], mean (±SD) 39.8 (±1.2) 39.4 (±2.1) 0.45$
Length at birth [cm], mean (±SD) 49.6 (±1.7) 49.7 (±2.0) 0.78$
Weight at birth [g], mean (±SD) 3403.5 (±334.2) 3343.3 (±581.2) 0.69$
Breastfeeding duration [months], mean (±SD) 8.6 (±2.7) 9.3 (±2.9) 0.44$
fAge at PCV administration [weeks], mean (±SD)    
 1st dose 9.6 (±1.8) 10.6 (±4.8) 0.34$
 2nd dose 18.9 (±2.4) 18.9 (±5.5) 0.97$
gHib administration, n, mean age [weeks] (±SD)    
 1st dose 20, 9.6 (±1.8) 21, 9.6 (±1.1) 0.96$
 2nd dose 20, 18.9 (±2.4) 21, 18.2 (±1.1) 0.28$
 3rd dose 18, 27.1 (±1.9) 21, 27.2 (±1.6) 0.87$
Respiratory symptoms, n, mean per infant (±SD)    
Total 127, 6.4 (±2.7) 134, 6.4 (±3.1) 0.97$
 Rhinitis 99, 5.0 (±2.4) 125, 6.0 (±2.9) 0.24$
hURTI 71, 3.6 (±2.2) 76, 3.6 (±2.4) 0.92$
iLRTI 7, 0.35 (±0.8) 21, 1.0 (±1.2) 0.05 $
 Wheezing 2, 0.1 (±0.3) 6, 0.3 (±0.7) 0.29$
  1. Statistically significant differences were indicated in italics
  2. SD standard deviation
  3. aParental education was categorized into low (less than 4 years of apprenticeship), middle (at least 4 years of apprenticeship), or high (tertiary education)
  4. bHA nutrition (hypoallergenic nutrition) was defined as feeding of hypoallergenic milk supplements at any time point within the first year of life
  5. cChildcare was defined as attending childcare at any time point within the first year of life
  6. dSmoking exposure due to the father and/or the mother smoking within the first year of life of the infant
  7. eMaternal atopy was defined as asthma, hay fever, or eczema
  8. fThe PCV (pneumococcal conjugate vaccine) vaccination schedule is at 2, 4, and 11–15 months Note that all infants obtained the first and the second but not the third dose within the first year of life
  9. gHib (Haemophilus influenzae type b) vaccination schedule is at 2, 4, 6, and 15–24 months of age. None of the infants got the fourth dose within the observed study period. In Switzerland, the vaccine is recommended as a combination vaccine with diphtheria, tetanus, pertussis, and poliomyelitis
  10. hURTI: Symptoms of upper respiratory tract infection (URTI) was defined as typical upper respiratory tract symptoms, whereas cough and/or wheeze had to be present
  11. iLRTI: Symptoms of lower respiratory tract infection (LRTI) was defined as cough, wheeze or breathing difficulties, combined with upper respiratory tract symptoms or elevated body temperature for more than two consecutive days
  12. #Statistical testing of categorical variables was performed by a 2 × 2, 2 × 3, or 2 × 4 chi-square test
  13. $Statistical testing of continuous variables was performed by unpaired t tests