Introduction
Immunisation is one of the most efficient and effective public health interventions to reduce child mortality and morbidity.1 Every year, an estimated 2–3 million lives are saved by immunisation.2 However, close to 20 million children under 1 year of age do not receive basic vaccinations. Incomplete vaccination, late vaccination and ‘zero dose’ children are concentrated in conflict-affected regions, low-income countries and socially marginalised populations in middle-income countries.2
In India, the percentage of fully immunised children 12–23 months of age increased from 44% in 2005–2006 to 62% in 2015–2016.3 However, despite this increase, inequities in coverage persist across states and by sociodemographic characteristics, including wealth and education.3 Regionally, coverage of critical vaccines, including Diphtheria Pertussis and Tetanus (DPT) and measles, among children 12–23 months old is much lower in India (87% each for DPT and measles) compared with neighbouring countries of Bangladesh (96% for DPT and 97% for measles) and Sri Lanka (99% for both).4
While timely and complete childhood immunisation is closely linked to health service provision, parental knowledge and practice also plays a role. Parents’ level of knowledge about vaccination needs, time availability, travel capacity to bring the child to vaccination sites and attitudes towards vaccination are key influencers on childhood vaccination. Positive association with full immunisation5 has been found with children whose parents had higher immunisation knowledge in many settings.6–8 Higher parental knowledge about child immunisation is associated with higher parental age, more years of education, being employed, having a greater number of children and higher household income.9–11 Full immunisation has also been found to be more prevalent among children whose parents owned mobile phones, after controlling for other socioeconomic factors in Mozambique.12 While India has one of the highest rates of vaccine confidence in the world, with over 80% of the population considering vaccines important, safe and effective,13 14 low awareness and poor access have been identified as drivers of some hesitancy.15
Mobile health (mHealth) interventions have been used to provide health information on vaccines, as well as send alerts and reminders to beneficiaries to improve immunisation timeliness.16 Programmes in Zimbabwe,17 Kenya,18 Nigeria19 and Bangladesh,20 which have used vaccination appointment reminders and immunisation-related prerecorded messages, have been found to positively influence immunisation uptake. But, in rural Haryana, India, a text message service, which sent reminders to care-givers and used Global Positioning Satellites to track children who had missed appointments was found to have no significant impact on full and timely vaccination of children.21 However, when these services were combined with a financial incentive, the intervention showed a positive impact.21 These mixed findings highlight the need for further evaluations of mHealth services in India, particularly, low cost direct-to-beneficiary mHealth programmes like Kilkari.
Kilkari is India and the world’s largest direct-to-beneficiary mobile communication programmes. Since its inception in 2012, Kilkari has reached over 10 million new and expectant mothers and their families with up to 72 weekly stage-based audio health information messages. Kilkari calls span from the 12th week of pregnancy up until the child’s first birthday and includes content on a range of health areas: family planning, child immunisation, nutrition, infant feeding, pregnancy care, entitlements and postnatal care. Immunisation messages are provided over 11 calls, which focus on the benefits of vaccination and diseases prevented by it, along with a reminder to the parents to take the child for next vaccination (online supplemental Annexure-1). In this study, we aim to assess the determinants of parental knowledge of immunisation, full immunisation and timely immunisation in the context of the Kilkari programme. We draw from cross-sectional survey data captured as part of an individually randomised controlled trial (RCT) of the Kilkari programme in four districts of Madhya Pradesh (MP), India.22