Vaccine 28 (2010) 7215–7220 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine Post-licensure comparison of the safety profile of diphtheria/tetanus/whole cell pertussis/haemophilus influenza type b vaccine and a 5-in-1 diphtheria/tetanus/acellular pertussis/haemophilus influenza type b/polio vaccine in the United Kingdom Nick Andrews a,* , Julia Stowe b , Lesley Wise c , Elizabeth Miller b a Statistics Unit, Health Protection Agency, Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, United Kingdom b Immunisation, Hepatitis and Blood Safety Department, Health Protection Agency, Centre for Infections, United Kingdom c Vigilance Risk Management of Medicines, Pharmacovigilance Risk Management Group, Medicines and Healthcare products Regulatory Agency, United Kingdom article info Article history: Received 9 June 2010 Received in revised form 10 August 2010 Accepted 11 August 2010 Available online 26 August 2010 Keywords: DTP Acellular pertussis combinations Safety abstract General practitioner consultation data were used to compare the reactogenicity in infants of a 5-in-1 acellular pertussis vaccine (DTaP 5 /Hib/IPV) introduced in the United Kingdom in 2004 to the 4-in-1 whole cell-pertussis vaccine (DTwP/Hib) that it replaced. For each vaccine the incidence in the week following vaccination was compared to other periods to obtain a relative incidence. A lower relative incidence of crying, fever and local reactions was seen with DTaP 5 /Hib/IPV than DTwP/Hib. Although there were no other significant differences between vaccines the relative incidence was significantly above one on the day of vaccination for convulsions following DTwP/Hib and for apnoea/collapse following DTaP 5 /Hib/IPV. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction In September 2004 a combined diphtheria, tetanus, 5 compo- nent acellular pertussis, Haemophilus influenza type b, inactivated poliovirus vaccine (DTaP 5 /Hib/IPV) manufactured by Sanofi Pas- teur MSD (Pediacel TM ) replaced the combined whole cell pertussis (wP) containing DTwP/Hib vaccine formerly given for primary immunisation with oral poliovirus vaccine in the United Kingdom (UK). DTaP 5 /Hib/IPV is the acellular pertussis combination vaccine of choice for the UK immunisation programme as it achieves a satisfactory antibody response to the Hib component under the accelerated UK primary schedule of 2/3/4 months [1], unlike some other DTaP/Hib combination vaccines used in the UK [2,3]. Further- more it contains five purified pertussis antigens—a formulation that has been shown in clinical trials to provide protection equivalent to that of the wP-containing vaccine previously used in the UK [4]. In a pivotal randomised trial that compared the immunogenic- ity [1] and reactogenicity [5] profile of DTaP 5 /Hib/IPV with that of the existing UK DTwP/Hib vaccine, local redness and swelling, and common systemic symptoms, occurred at a significantly lower rate after DTaP 5 /Hib/IPV. In the current study we have assessed * Corresponding author. Tel.: +44 020 8327 7419; fax: +44 020 8200 7868. E-mail address: nick.andrews@hpa.org.uk (N. Andrews). the impact that the reduction in common and generally mild symptoms measured in clinical trials has on consultations for suspected vaccine reactions seen in general practice. For this, the General Practice Research Database (GPRD) was used to compare the incidence of consultations for events compatible with a vaccine reaction in children under 1 year of age in DTaP 5 /Hib/IPV and DTwP/Hib vaccinated cohorts. 2. Methods We identified consultations for events of interest and details of vaccinations from the GPRD, which is one of the world’s largest primary care databases [6]. It holds data on consultations, referrals, prescriptions and vaccinations for over 3 million active patients in practices throughout the UK (5.7% of the population). We selected children in the GPRD whose practice record had an ‘acceptable’ sta- tus and with an ‘up to standard’ date earlier than the child’s date of birth. The ‘up to standard’ date is the date when the practice complied with specific quality measures based on completeness, continuity and plausibility in key areas. Acceptable status is given to a patient when certain data quality conditions have been met, such as no events recorded before birth date, age is less than 115 years and the gender field is completed. Children included in the analysis were those born from January 2003 to March 2006 who were registered from birth until the age of 12 months or death if earlier. This gave an estimated cohort size of 121,700 children from 0264-410X/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.vaccine.2010.08.062