The potential effect of temporary immunity as a result of bias associated with healthy users and social determinants on observations of influenza vaccine effectiveness; could unmeasured confounding explain observed links between seasonal influenza vaccine and pandemic H1N1 infection?

Table 1 Baseline parameter assumptions

Characteristic	Parameter
Proportions in population	Proportion of the population with a social determinant that would confound the association)	12%
	Proportion of the population classified as healthy users	40%
	Seasonal vaccine baseline coverage	40%
Effect sizes	Vaccination coverage among the population with social determinants (half baseline coverage)	10%
	Proportion of controls that would be classified as cases due to having social determinants	20%
	Vaccination coverage among population of healthy users (10% above baseline)	50%
	Proportion of cases that would be classified as controls due to being a healthy users	20%
	Seasonal influenza vaccine effectiveness against seasonal influenza	60%
	Additional effect of non-influenza ILI	10%

ISSN: 1471-2458