Sex-Differential Effect on Infant Mortality of Oral Polio Vaccine Administered with BCG at Birth in Guinea-Bissau. A Natural Experiment
2008

Impact of Oral Polio Vaccine on Infant Mortality in Guinea-Bissau

Sample size: 4345 publication 10 minutes Evidence: moderate

Author Information

Author(s): Benn Christine Stabell, Fisker Ane Bærent, Rodrigues Amabelia, Ravn Henrik, Sartono Erliyani, Whittle Hilton, Yazdanbakhsh Maria, Aaby Peter

Primary Institution: Bandim Health Project, Statens Serum Institut, Copenhagen, Denmark

Hypothesis

Not receiving OPV at birth would increase mortality, particularly for girls.

Conclusion

The study found that OPV at birth had a sex-differential effect on mortality, decreasing mortality in boys but potentially increasing it in girls.

Supporting Evidence

  • A total of 962 (22.1%) of the 4345 enrolled children did not receive OPV at birth.
  • Missing OPV at birth was associated with a tendency for decreased mortality.
  • There was a highly significant interaction between OPV at birth and sex (p=0.006).
  • Not receiving OPV at birth was associated with a weak tendency for increased mortality in girls but significantly decreased mortality in boys.

Takeaway

Giving the polio vaccine at birth helps boys live longer, but it might not be good for girls.

Methodology

The study used Cox proportional hazards models to analyze mortality rates among infants who received or did not receive OPV at birth.

Potential Biases

There may be bias due to differences in maternal education and health status among those who did and did not receive OPV.

Limitations

The study was observational and may have uncontrolled confounding factors.

Participant Demographics

Infants enrolled in a vitamin A supplementation trial in Guinea-Bissau, with a significant proportion from low-education backgrounds.

Statistical Information

P-Value

0.006

Confidence Interval

0.46–1.03

Statistical Significance

p=0.006

Digital Object Identifier (DOI)

10.1371/journal.pone.0004056

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