title: Changes in meningococcal C epidemiology and vaccine effectiveness after vaccine introduction and schedule modification.
abstract: OBJECTIVE
  Meningococcal C conjugate vaccine was included in December 2000 in the Spanish childhood vaccination at 2, 4 and 6 months of age. In 2006, routine vaccination was modified to two doses at 2 and 4-6 months and a booster dose during the second year of age. Additionally, successive catch-up campaigns were launched to extend protection to older groups. This study provides long-term information about the vaccine effectiveness (VE) and the impact of vaccination in meningococcal C disease epidemiology in Spain.
  
  
  METHODS
  We assessed surveillance data from season 1996/97 to season 2012/13 to describe changes in incidence and lethality of the disease. The vaccine-effectiveness study covered all cases notified from January 1st of 2001 onwards and evaluated vaccine effectiveness in both routines and in catch-up campaigns. To investigate the decline in protection over time, we compared the vaccine effectiveness within 1 year and more than one year since vaccination.
  
  
  RESULTS
  The incidence of meningococcal serogroup C disease decreased first in those age-groups targeted for vaccination. But after 2006/07 season the decrease in incidence was generalised. Vaccine effectiveness was high in all vaccination programmes, although 2, 4-6 months (+ booster dose) routine showed higher overall vaccine effectiveness than 2, 4 and 6 months routine (99.3% vs. 90.2%). VE >1 year since vaccination was lower in 2, 4 and 6 months compared to 2 and 4-6 months (+ booster) routine (81.4% vs. 89.1%). For catch-up campaigns, VE increased and loss of VE decreased with the age of administration. Overall VE was 94.83 (CI95%: 93.37, 95.97), 98.82 (CI95%: 97.96, 99.31) and 90.89 (CI95%: 87.79, 93.21) for ≤ 1 and >1 year since vaccination, respectively.
  
  
  CONCLUSIONS
  The meningococcal C conjugate vaccination programme has been extremely successful in controlling the disease and continues to be evaluated and adapted to the changes in the epidemiology of the disease to ensure long-term vaccine protection.
authors.affiliation: National Centre for Epidemiology. Carlos III Health Institute (ISCIII-CNE), Spain. Electronic address: mgarrido@isciii.es.
authors.forename: M
authors.initials: M
authors.lastname: Garrido-Estepa
authors.affiliation: National Centre for Epidemiology. Carlos III Health Institute (ISCIII-CNE), Spain.
authors.forename: I
authors.initials: I
authors.lastname: León-Gómez
authors.affiliation: Preventive Medicine and Public Health, University School of Medicine, Autónoma University, Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Herruzo
authors.affiliation: National Centre for Epidemiology. Carlos III Health Institute (ISCIII-CNE), Spain.
authors.forename: R
authors.initials: R
authors.lastname: Cano
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D006801:Humans; D017589:Immunization Programs / Q000706:statistics & numerical data*; D007115:Immunization Schedule; D015994:Incidence; D007223:Infant; D016015:Logistic Models; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000627:therapeutic use*; D008875:Middle Aged; D038542:Neisseria meningitidis, Serogroup C; D013030:Spain / Q000453:epidemiology; D018074:Vaccines, Conjugate / Q000627:therapeutic use; D055815:Young Adult
chemical_list: D022401:Meningococcal Vaccines; D018074:Vaccines, Conjugate; C410218:serogroup C meningococcal conjugate vaccine
keywords: Logistic regression; meningococcal disease; serogroup C; vaccine effectiveness