Table 2.

Power for analysis of primary exposure-outcome associations

Primary exposures (geohelminth infections)	Outcome	Sample size available	Analysis sample size	Exposure prevalence	Expected prevalence of outcomes (exposed vs. unexposed groups)	Α	Power
Maternal	Vaccine antibodies @ 7 mths
	Hib	2,300	1,000	50%	65% vs. 75%	0.01	80%
	Rotavirus	2,300	1,000	50%	40% vs. 60%	0.01	> 99%
Maternal	Vaccine antibodies @ 2 yrs
	TT	1,955	1,000	50%	85% vs. 95%	0.01	> 99%
	HBV	1,955	1,750	50%	80% vs. 85%	0.05	80%
	OPV type 3	1,955	500	50%	80% vs. 95%	0.01	> 99%
Infant	Vaccine antibodies @ 5 yrs
	TT	1,725	1,000	35%	60% vs. 80%	0.01	99%
	HBV	1,725	1,500	35%	70% vs. 80%	0.01	95%
	OPV type 3	1,725	1,000	35%	50% vs. 70%	0.01	> 99%
Maternal	SPT @ 3 years	1,840	1,840	50%	15% vs. 25%	0.01	99%
Infant	SPT @ 3 years	1,840	1,840	35%	15% vs. 25%	0.01	> 99%
Maternal	Eczema @ 3 years	1,840	1,840	50%	25% vs. 35%	0.01	99%
Maternal	Asthma @ 5 years	1,725	1,725	50%	17% vs. 23% #	0.05	86%
Infant	Asthma @ 5 years	1,725	1,725	35%	17% vs. 23% #	0.05	83%
Infant	Asthma @ 5 years	1,725	1,207	20%	25% vs. 15% #	0.01	93%

Random samples of the study population will be selected for analysis of the protective levels of vaccine antibodies. Based on data from the cohort we estimate that 20% of children will have allergen skin test reactivity to any allergen at 5 years, that 30% of children will have at least one documented episode of eczema by 3 years of age and that 20% of children will have asthma at 5 years. Based on data from the cohort we estimate that ~50% of mothers are infected with any geohelminth parasite and ~30% of children will have at least one documented geohelminth infection during the first 2 years of life.

#-expected effects of geohelminth infections on asthma prevalence using data from cross-sectional analyses in Ecuador [58] and Brazil [59].