{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T05:45:58Z","timestamp":1785908758820,"version":"3.56.0"},"reference-count":52,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,4,17]],"date-time":"2023-04-17T00:00:00Z","timestamp":1681689600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001349","name":"National Medical Research Council","doi-asserted-by":"publisher","award":["CGAug16C008"],"award-info":[{"award-number":["CGAug16C008"]}],"id":[{"id":"10.13039\/501100001349","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Vaccines"],"abstract":"<jats:p>Immunization schedules affect community vaccine uptake rates, especially in children who have defaulted on their regular immunization timelines. In 2020, Singapore revised its National Childhood Immunization Schedule (NCIS) to incorporate two new combination vaccines: the hexavalent hepatitis, diphtheria, acellular pertussis, tetanus (DTaP), hemophilus influenzae b (Hib), inactivated poliovirus (IPV) (6-in-1), and the quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines, thus reducing the mean number of clinic visits and vaccine doses by two. Our database study aims to evaluate the impact of the 2020 NCIS on catch-up vaccination uptake rates in children at 18 and 24 months of age and the catch-up immunization rates of individual vaccines at two years. Vaccination data from two cohorts, in 2018 (n = 11,371) and in 2019 (n = 11,719), were extracted from the Electronic Medical Records. Catch-up vaccination rates increased by 5.2% and 2.6% in children on the new NCIS at 18 and 24 months, respectively. The uptake of individual 5-in-1 (DTaP, IPV, Hib), MMR, and pneumococcal vaccines increased by 3.7%, 4.1%, and 1.9% at 18 months. Reduced vaccination doses and visits in the new NCIS bring direct and indirect benefits to parents and promote vaccination adherence for their children. These findings highlight the importance of timelines in improving catch-up vaccination rates in any NCIS.<\/jats:p>","DOI":"10.3390\/vaccines11040859","type":"journal-article","created":{"date-parts":[[2023,4,17]],"date-time":"2023-04-17T06:27:47Z","timestamp":1681712867000},"page":"859","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["The Impact of a Revised National Childhood Immunization Schedule on Vaccination Defaulters"],"prefix":"10.3390","volume":"11","author":[{"given":"Ngiap Chuan","family":"Tan","sequence":"first","affiliation":[{"name":"SingHealth Polyclinics, Singapore 150167, Singapore"},{"name":"SingHealth Duke-NUS Family Medicine Academic Clinical Programme, Singapore 150167, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeremy","family":"Pang","sequence":"additional","affiliation":[{"name":"Duke-NUS Medical School, Singapore 169857, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eileen","family":"Koh","sequence":"additional","affiliation":[{"name":"SingHealth Duke-NUS Family Medicine Academic Clinical Programme, Singapore 150167, Singapore"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2132","DOI":"10.1080\/21645515.2015.1044180","article-title":"The value of childhood combination vaccines: From beliefs to evidence","volume":"11","author":"Maman","year":"2015","journal-title":"Hum. Vaccin. Immunother."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"4105","DOI":"10.1016\/S0264-410X(03)00377-3","article-title":"The value of vaccination: A global perspective","volume":"21","author":"Ehreth","year":"2003","journal-title":"Vaccine"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"87","DOI":"10.3121\/cmr.1.2.87","article-title":"Smallpox vaccine: The good, the bad, and the ugly","volume":"1","author":"Belongia","year":"2003","journal-title":"Clin. Med. Res."},{"key":"ref_4","unstructured":"(2023, January 03). Childhood Immunisation\u2014Ministry of Health, Available online: https:\/\/www.moh.gov.sg\/docs\/librariesprovider5\/resources-statistics\/reports\/childhood-immunisation.pdf."},{"key":"ref_5","unstructured":"(2023, January 06). Vaccines and Immunization. Available online: https:\/\/www.who.int\/health-topics\/vaccines-and-immunization#tab=tab_1."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"e16","DOI":"10.1542\/peds.114.1.e16","article-title":"Underimmunization among children: Effects of vaccine safety concerns on immunization status","volume":"114","author":"Gust","year":"2004","journal-title":"Pediatrics"},{"key":"ref_7","unstructured":"Glanz, K., Rimer, B.K., and Viswanath, K. (2015). Health Behavior: Theory, Research, and Practice, John Wiley & Sons."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1542\/peds.2009-1653","article-title":"Measles Outbreak in a Highly Vaccinated Population, San Diego, 2008: Role of the Intentionally Undervaccinated","volume":"125","author":"Sugerman","year":"2010","journal-title":"Pediatrics"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Kroger, A., Bahta, L., Long, S., and Sanchez, P. (2017). Practices and Advisory Committee on Immunization Practices. General Recommendations on Immunization: Recommendations of the Advisory Committee on Immunization Practices (ACIP). Pediatr. Clin. Pract. Guidel. Policies, 1516.","DOI":"10.1542\/9781610020862-part06-general"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1136","DOI":"10.1001\/archpedi.159.12.1136","article-title":"Economic evaluation of the 7-vaccine routine childhood immunization schedule in the United States, 2001","volume":"159","author":"Zhou","year":"2005","journal-title":"Arch. Pediatr. Adolesc. Med."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"973","DOI":"10.1542\/peds.106.5.973","article-title":"Economic Impact of Influenza Vaccination in Preschool Children","volume":"106","author":"Cohen","year":"2000","journal-title":"Pediatrics"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"577","DOI":"10.1542\/peds.2013-0698","article-title":"Economic evaluation of the routine childhood immunization program in the United States, 2009","volume":"133","author":"Zhou","year":"2014","journal-title":"Pediatrics"},{"key":"ref_13","unstructured":"OECD\/WHO (2020) (2020). Health at a Glance: Asia\/Pacific 2020: Measuring Progress Towards Universal Health Coverage, OECD Publishing."},{"key":"ref_14","unstructured":"(2023, January 06). National Childhood Immunisation Schedule. 2020. National Immunisation Registry, Singapore, Available online: https:\/\/www.nir.hpb.gov.sg\/nirp\/eservices\/immunisationSchedule."},{"key":"ref_15","unstructured":"(2023, January 03). Infectious Diseases Act 1976\u2014Singapore Statutes Online, Available online: https:\/\/sso.agc.gov.sg:5443\/Act\/IDA1976."},{"key":"ref_16","first-page":"S6","article-title":"Benefits of combination vaccines: Effective vaccination on a simplified schedule","volume":"9","author":"Dodd","year":"2003","journal-title":"Am. J. Manag. Care"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/S0891-5245(03)00002-6","article-title":"Communicating the benefits of combination vaccines to parents and health care providers","volume":"17","author":"Parsons","year":"2003","journal-title":"J. Pediatr. Health Care"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"507","DOI":"10.1097\/01.inf.0000222413.47344.23","article-title":"The use of combination vaccines has improved timeliness of vaccination in children","volume":"25","author":"Kalies","year":"2006","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_19","doi-asserted-by":"crossref","unstructured":"Tan, N.C., Tan, Q., Aau, W.K., and Ng, C.W.M. (2022). The implementation and impact of a revised national childhood immunization schedule in an urban Asian Community. Vaccines, 10.","DOI":"10.3390\/vaccines10071148"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1542\/peds.94.1.53","article-title":"Immunization coverage and its relationship to preventive health care visits among inner-city children in Baltimore","volume":"94","author":"Guyer","year":"1994","journal-title":"Pediatrics"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"110","DOI":"10.11622\/smedj.2014030","article-title":"Pair up for primary care excellence: Perspectives from a primary healthcare provider in Singapore","volume":"55","author":"Tan","year":"2014","journal-title":"Singap. Med. J."},{"key":"ref_22","unstructured":"Plan Your Visit\u2014Singhealth (2023, January 29). Plan Your Visit, Make An Appointment. Available online: https:\/\/polyclinic.singhealth.com.sg\/patient-care\/your-clinic-visit\/Pages\/Plan-Your-Visit.aspx."},{"key":"ref_23","unstructured":"(2023, January 08). Electronic Health Intelligence System. Available online: https:\/\/www.ihis.com.sg\/Project_Showcase\/Healthcare_Systems\/Pages\/eHINTS.aspx."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12889-016-3597-5","article-title":"Parental knowledge, attitudes and perception of pneumococcal disease and pneumococcal conjugate vaccines in Singapore: A questionnaire-based assessment","volume":"16","author":"How","year":"2016","journal-title":"BMC Public Health"},{"key":"ref_25","unstructured":"(2023, January 03). MOH, Available online: https:\/\/www.moh.gov.sg\/resources-statistics\/subsidised-vaccine-list."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"127","DOI":"10.1093\/heapol\/czg017","article-title":"Working with the private sector for child health","volume":"18","author":"Waters","year":"2003","journal-title":"Health Policy Plan."},{"key":"ref_27","unstructured":"(2023, January 03). COVID-19 Circuit Breaker: Closure of Workplace Premises, Available online: http:\/\/www.gov.sg\/article\/covid-19-circuit-breaker-closure-of-workplace-premises."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"780","DOI":"10.1016\/j.vaccine.2020.12.054","article-title":"Childhood vaccinations: Hidden impact of COVID-19 on children in Singapore","volume":"39","author":"Zhong","year":"2021","journal-title":"Vaccine"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"4857","DOI":"10.1111\/jocn.13958","article-title":"A descriptive qualitative study of perceptions of parents on their child\u2019s vaccination","volume":"26","author":"Kurup","year":"2017","journal-title":"J. Clin. Nurs."},{"key":"ref_30","unstructured":"(2023, January 03). Make Change Appointment. Available online: https:\/\/polyclinic.singhealth.com.sg\/patient-care\/e-services\/make-change-appointment\/make-change-appointment."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"S431","DOI":"10.1093\/infdis\/jiac306","article-title":"Safety Surveillance of Varicella Vaccines in the Vaccine Adverse Event Reporting System, United States, 2006\u20132020","volume":"226","author":"Moro","year":"2022","journal-title":"J. Infect. Dis."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e1721","DOI":"10.1097\/MD.0000000000001721","article-title":"Combination Measles-Mumps-Rubella-Varicella Vaccine in Healthy Children: A Systematic Review and Meta-analysis of Immunogenicity and Safety","volume":"94","author":"Ma","year":"2015","journal-title":"Medicine"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"1166","DOI":"10.1097\/INF.0b013e318267fd8b","article-title":"Safety of a 2-dose regimen of a combined measles, mumps, rubella and varicella live vaccine manufactured with recombinant human albumin","volume":"31","author":"Gabutti","year":"2012","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1097\/01.inf.0000220209.35074.0b","article-title":"The safety and immunogenicity of a quadrivalent measles, mumps, rubella and varicella vaccine in healthy children: A study of manufacturing consistency and persistence of antibody","volume":"25","author":"Lieberman","year":"2006","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"e007202","DOI":"10.1136\/bmjopen-2014-007202","article-title":"Immunogenicity and safety of early vaccination with two doses of a combined measles-mumps-rubella-varicella vaccine in healthy Indian children from 9 months of age: A phase III, randomised, non-inferiority trial","volume":"5","author":"Lalwani","year":"2015","journal-title":"BMJ Open"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"6504","DOI":"10.1016\/j.vaccine.2009.07.076","article-title":"A combined measles, mumps, rubella and varicella vaccine (Priorix-Tetra): Immunogenicity and safety profile","volume":"27","author":"Czajka","year":"2009","journal-title":"Vaccine"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e272","DOI":"10.1097\/INF.0000000000001682","article-title":"A Randomized Controlled Study of a Fully Liquid DTaP-IPV-HB-PRP-T Hexavalent Vaccine for Primary and Booster Vaccinations of Healthy Infants and Toddlers in Latin America","volume":"36","author":"Feroldi","year":"2017","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"397","DOI":"10.1007\/s40272-019-00353-7","article-title":"DTaP-IPV-HepB-Hib Vaccine (Hexyon): An Updated Review of its Use in Primary and Booster Vaccination","volume":"21","author":"Syed","year":"2019","journal-title":"Paediatr. Drugs"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"S77","DOI":"10.1016\/j.amepre.2020.09.003","article-title":"Vaccine Hesitancy and Concerns About Vaccine Safety and Effectiveness in Shanghai, China","volume":"60","author":"Wagner","year":"2021","journal-title":"Am. J. Prev. Med."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/s12889-017-4083-4","article-title":"Active surveillance study of adverse events following immunisation of children in the Czech Republic","volume":"17","author":"Danova","year":"2017","journal-title":"BMC Public Health"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"5000","DOI":"10.1016\/j.vaccine.2014.07.020","article-title":"Active surveillance of adverse events following childhood immunization in Singapore","volume":"32","author":"Thoon","year":"2014","journal-title":"Vaccine"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"w30090","DOI":"10.4414\/SMW.2021.w30090","article-title":"Smartphone-based Active Vaccine Safety Surveillance (smartvax) at a Swiss adult vaccination clinic\u2014A pilot study","volume":"151","author":"Guedel","year":"2021","journal-title":"Swiss Med. Wkly."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1910","DOI":"10.1016\/j.vaccine.2021.02.057","article-title":"Multi-domain narrative review of vaccine hesitancy in childhood","volume":"39","author":"Hasnan","year":"2021","journal-title":"Vaccine"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"e243","DOI":"10.1097\/INF.0000000000003499","article-title":"Effective Approaches to Combat Vaccine Hesitancy","volume":"41","author":"Gagnon","year":"2022","journal-title":"Pediatr. Infect. Dis. J."},{"key":"ref_45","doi-asserted-by":"crossref","unstructured":"Griva, K., Tan, K.Y.K., Chan, F.H.F., Periakaruppan, R., Ong, B.W.L., Soh, A.S.E., and Chen, M.I. (2021). Evaluating Rates and Determinants of COVID-19 Vaccine Hesitancy for Adults and Children in the Singapore Population: Strengthening Our Community\u2019s Resilience against Threats from Emerging Infections (SOCRATEs) Cohort. Vaccines, 9.","DOI":"10.3390\/vaccines9121415"},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Olson, O., Berry, C., and Kumar, N. (2020). Addressing Parental Vaccine Hesitancy towards Childhood Vaccines in the United States: A Systematic Literature Review of Communication Interventions and Strategies. Vaccines, 8.","DOI":"10.3390\/vaccines8040590"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Gun, S.Y., Moosa, A.S., Poh, C.W., Ng, S.L., and Tan, N.C. (2023). A Voice-Annotated Digital Decision Aid to romote Child influenza Vaccination: A Feasibility Study. Vaccines, 11.","DOI":"10.3390\/vaccines11030565"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"S152","DOI":"10.1016\/j.clinthera.2009.07.022","article-title":"Inadequate pain management during routine childhood immunizations: The nerve of it","volume":"31","author":"Taddio","year":"2009","journal-title":"Clin. Ther."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"4807","DOI":"10.1016\/j.vaccine.2012.05.011","article-title":"Survey of the prevalence of immunization non-compliance due to needle fears in children and adults","volume":"30","author":"Taddio","year":"2012","journal-title":"Vaccine"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"847257","DOI":"10.3389\/fped.2022.847257","article-title":"Immersive Virtual Reality in Alleviating Pain and Anxiety in Children during Immunization in Primary Care: A Pilot Randomized Controlled Trial","volume":"10","author":"Chang","year":"2022","journal-title":"Front. Pediatr."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"e006860","DOI":"10.1136\/bmjgh-2021-006860","article-title":"Parent-level barriers to uptake of childhood vaccination: A global overview of Systematic Reviews","volume":"6","author":"Kaufman","year":"2021","journal-title":"BMJ Global Health"},{"key":"ref_52","unstructured":"Guglielmi, G. (2023, January 29). Pandemic Drives Largest Drop in Childhood Vaccinations in 30 Years, Nature News, Available online: https:\/\/www.nature.com\/articles\/d41586-022-02051-w."}],"container-title":["Vaccines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-393X\/11\/4\/859\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:17:27Z","timestamp":1760123847000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-393X\/11\/4\/859"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,4,17]]},"references-count":52,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["vaccines11040859"],"URL":"https:\/\/doi.org\/10.3390\/vaccines11040859","relation":{},"ISSN":["2076-393X"],"issn-type":[{"value":"2076-393X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2023,4,17]]}}}