Co-administration of paediatric vaccines in Shanghai, China

•Immunization clinics in Shanghai informally discourage vaccine co-administration.•Less than 20% of DTP, OPV, Hib vaccine, PCV, and rotavirus vaccine were co-administered.•Non-locals had more co-administration than locals.•Co-administration increased over time.•More co-administration could lead to greater timeliness and higher vaccine uptake.