Inclusion of vaccines into the childhood immunisation programme and association with mothers’ decision to vaccinate their children

Abstract

BACKGROUND AND AIMS: The Scientific Committee on Vaccine Preventable Diseases determines whether vaccines should be included in the Hong Kong Childhood Immunisation Programme (CIP). Vaccine in the CIP are administered at Maternal Child Health Centres at no cost to the parents. Vaccines not in the CIP are mainly available in the private sector and parents pay out-of-pocket if they want their children vaccinated. We investigated the association between vaccination uptake/ intention and vaccine inclusion in the CIP. METHODS: A sample of 500 postpartum mothers were recruited from postnatal wards at two public hospitals from May to August 2014. When the children reached 6 months old, postal questionnaires with telephone follow-up if necessary collected details of vaccination uptake (vaccines scheduled below 6 months) and maternal vaccination intention (vaccines scheduled after 6 months). Chi-square tests and logistic mixed models were performed using statistical software R version 3.2.1. RESULTS: One family left Hong Kong and 6 mothers quitted the study before 6 months. Of those mothers followed-up, 372 (75%) responded to the 6-month questionnaires of which 314 (84%) provided copies of immunisation records. Uptake of vaccines scheduled before 6 months and in CIP (Bacillus Calmette-Guérin, Hepatitis B, Diphtheria, Tetanus, acellular Pertussis and injectable Polio, conjugate pneumococcal) was 100% but significantly less for those not in CIP (Haemophilus influenzae type b (28%) and rotavirus (47%)). Excluding vaccines for travelers and older children, four vaccines are available for routine use after 6 months of age (Measles, Mumps and Rubella vaccine [MMR], varicella, influenza and Hepatitis A vaccines). 88% and 86% mothers intended to give MMR and varicella to their children in the future respectively but less intended to give vaccines not in the CIP (influenza (33%) and Hepatitis A (32%)). Inclusion of a vaccine in the CIP was significantly associated with both the overall vaccination uptake (p<0.0001) and intention (p<0.0001). Family household income was not a moderator of the association between CIP inclusion and vaccination intention (p=0.064). CONCLUSIONS: Inclusion of a vaccine in the CIP was strongly associated with both vaccination uptake and maternal intention.