Appendix A.

Definitions of Themes and Subthemes.

Themes and definitions	Subthemes and definitions
Vaccine safety: parental concerns regarding the potential physical harm that the composition and the frequency of administration of vaccines may impose on their child	Vaccine quality/contents: concerns regarding the efficacy and the ingredients of vaccines Health-related consequences: concerns or beliefs regarding consequential effects of vaccines, such as disease, disorder, illness, and pain Unnatural/overwhelming for body: concerns that the number of vaccines is unnecessary and harmful Incomplete/inadequate data on vaccine safety: belief that data on vaccine safety is incomplete or inadequate
Relative influence of information sources, decision-makers, and timing: defined as reasons pertaining to parent decision-making roles, information sources used, and timing of vaccination	Parent claims to have all the information needed for decision to refuse/delay: parent believes they possess sufficient knowledge to make informed decision and thus does not desire any more information or counseling from provider Need to consult family member who isn’t present: parent would like to consult their partner before proceeding with vaccine(s) Parental promise and convenience: parent does not want to backtrack a promise to child or does not want child to experience side effects during upcoming travel or child activity Discordance: lack of agreement among partners regarding vaccinating child
Low perceived risk of contracting VPD: reasons regarding parental perception around the low probability their child will contract disease	Due to limited exposure to susceptibility factors: believes child will not contract disease because exposure to susceptibility factors is considered insignificant Due to proximity to outbreak: believes child will not contract disease because the outbreak is a considerable distance away from child’s everyday environment Differential risks among VPDs: parent assigns different degrees of risk to VPDs and chooses to get vaccinated for the disease(s) that is perceived to be the worst or most likely to be contracted
Lack of trust: parent’s lack of trust in provider and/or government	Lack of established relationship with provider: parent is untrustworthy of provider as their relationship has yet to develop Government mis-/distrust: parent is untrustworthy of government and thus the information that is being passed along to providers
Religious objection: parental religious concerns regarding vaccines	Usage of porcine products: vaccines such as MMR contain gelatin, which is considered impure by some religious individuals Usage of aborted fetal cells: vaccines such as Varicella are grown in fetal embryo fibroblast cells, which is a practice considered impure by some religious individuals