Declining newborn intramuscular vitamin K prophylaxis predicts subsequent immunisation refusal: A retrospective cohort study

Aim Low rates of childhood immunisation are linked to outbreaks of infectious disease. Identifying and addressing barriers to immunisation may lead to improved immunisation rates. Immunisation and newborn vitamin K prophylaxis have many similarities. We aimed to investigate whether parents who decline newborn vitamin K are also more likely to decline subsequent childhood immunisations. Methods We undertook a retrospective cohort study, examining the relationship between vitamin K administration and immunisation uptake by parents of babies born over a 2-year period (January 2010–December 2011) in Dunedin, New Zealand (NZ). Both written and electronic data from a single birthing unit and the NZ National Immunisation Register (NIR) were analysed to ascertain the relationship between declining newborn vitamin K prophylaxis and subsequent immunisation uptake. Results Records for 3575 babies were examined. Ninety-two per cent of infants received intramuscular, and 5% received oral vitamin K. An increased risk ratio for non-immunisation of 14.1 (95% confidence interval 7.8–25.9) for babies whose parents declined vitamin K was identified. Receiving oral vitamin K was also associated with subsequent non-immunisation, with a risk ratio of 3.5 (95% confidence interval 1.7–7.3). Conclusions Parents who decline newborn vitamin K are more likely to decline immunisation for their child. These parents, as well as those that elect for oral vitamin K, are a small but easily identifiable group to whom additional education about the benefits of immunisation could be offered. This is especially pertinent at a time when there is a resurgence of immunisation preventable diseases.