Community cohort study of rotavirus and other enteropathogens: are routine vaccinations associated with sex-differential incidence rates?
OBJECTIVE
Community studies in West Africa have demonstrated that routine vaccinations may have non-targeted effects, the female-male mortality ratio being reduced after administration of BCG and increased after diphtheria-tetanus-pertussis (DTP). We examined whether immunisation status was associated with infection with rotavirus and other enteropathogens.


METHODS
We recruited 200 children shortly after birth and followed them until 2 years of age with weekly morbidity interviews and stool sampling. Vaccination status for each child was classified according to the most recent vaccination as documented by vaccination card.


METHODS
The female-male incidence rate ratios (IRR) of infection with an enteropathogen and of enteropathogen-associated diarrhoea were estimated for children according to whether they had received BCG or DTP as their last vaccination.


RESULTS
For children who received BCG as their last vaccine, the adjusted female-male IRRs for primary rotavirus-infection and diarrhoea were 1.05 (95% CI: 0.21-5.28) and 0.0 (95% CI: 0-3.02), respectively. For children who received DTP as their last vaccine, the adjusted female-male IRRs were 1.93 (0.89-4.21) and 1.92 (0.70-5.32), respectively, for rotavirus-associated infection and diarrhoea. Restricted to the rotavirus season, the female-male IRRs for rotavirus infection and diarrhoea were 2.56 (1.17-5.63) and 2.63 (0.94-7.34), respectively. The female-male IRR for rotavirus-associated diarrhoea differed significantly among BCG and DTP recipients (p=0.02). Infections with enteropathogens not associated with diarrhoea were associated with lower female-male IRRs after BCG of 0.82 (0.55-1.23) and higher female-male IRRs after DTP vaccination of 1.32 (1.03-1.70) for primary infection (p=0.05). Though there were few infections with other diarrhoea-causing enteropathogens, these were also associated with a lower female-male IRR after BCG of 0.62 (0.26-1.52) and a higher female-male IRR after DTP vaccination of 1.51 (1.04-2.20) for all infection.


CONCLUSIONS
Routine immunisations may affect morbidity for non-targeted infections. As in studies of infant mortality, BCG is associated with lower risk for girls, whereas, DTP is associated with higher risk for girls relative to boys.
Rodrigues
Amabelia
A
Bandim Health Project, Danish Epidemiology Science Centre, Statens Serum Institut, Apartado 861, Bissau, Guinea-Bissau.
Fischer
Thea K
TK
Valentiner-Branth
Palle
P
Nielsen
Jens
J
Steinsland
Hans
H
Perch
Michael
M
Garly
May-Lill
ML
Mølbak
Kåre
K
Aaby
Peter
P
D001500:BCG Vaccine / Q000276:immunology; D015331:Cohort Studies; D003457:Cryptosporidiosis / Q000453:epidemiology; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000276:immunology; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D012400:Rotavirus Infections / Q000453:epidemiology*; D012727:Sex Characteristics; D014611:Vaccination
D001500:BCG Vaccine; D015721:Diphtheria-Tetanus-Pertussis Vaccine