title: Crossover vaccination with quadrivalent meningococcal vaccine (against A/C/Y/W-135) following recent application of bivalent meningococcal vaccine (against A/C): assessment of safety and side effect profile.
abstract: BACKGROUND
  Until May 2000, bivalent A/C meningococcal vaccine was the only available vaccine in Singapore for hajj travelers to Saudi Arabia. Recent worldwide reports of serogroup W-135 meningococcal meningitis associated with hajj returnees necessitated switching to quadrivalent A/C/Y/W-135 vaccine and crossover vaccination of travelers to Saudi Arabia. No safety data are available for quadrivalent vaccine following recent vaccination with bivalent vaccine. We assessed the safety and side effect profile of bivalent, quadrivalent, and quadrivalent meningococcal vaccine after recent vaccination with bivalent vaccine.
  
  
  METHODS
  A postvaccination telephone questionnaire survey was performed for all travelers who received either bivalent (B), quadrivalent (Q), or quadrivalent with recent (as defined by less than 6 months before) bivalent meningococcal vaccine (BQ) between 22 May and 8 June 2000 in preparation for the umrah (minor pilgrimage). Patients were asked about local reactions (pain, erythema, swelling at injection site graded in mild, moderate, and severe) and systemic reactions (fever, headache, graded in mild and severe).
  
  
  RESULTS
  Of 546 persons vaccinated, 323 were interviewed. Median time interval between interview and vaccination was 10 days. Of those interviewed, 64 patients received bivalent (B), 213 quadrivalent (Q), and 46 quadrivalent after recent bivalent vaccine (BQ). The median interval time between previous bivalent and quadrivalent vaccine was 5 weeks. There was no statistically significant difference in the prevalence of side effects between the three groups. Mild pain at injection site was recorded in B as 21.8%, Q as 23%, BQ as 21.7%; low grade fever in B as 7.8%, Q as 9.8%, and BQ as 15.2%.
  
  
  CONCLUSIONS
  Bivalent and quadrivalent meningococcal vaccine are well tolerated. Crossover vaccination of quadrivalent meningococcal vaccine after recent vaccination with bivalent vaccine does not increase the prevalence of adverse reactions and is therefore safe.
authors.affiliation: Travellers' Health and Vaccination Centre, Department of Infectious Diseases, Tan Tock Seng Hospital, Singapore.
authors.forename: Annelies
authors.initials: A
authors.lastname: Wilder-Smith
authors.forename: Nicholas I
authors.initials: NI
authors.lastname: Paton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D008297:Male; D008585:Meningitis, Meningococcal / Q000517:prevention & control*; D022401:Meningococcal Vaccines / Q000009:adverse effects* / Q000145:classification*; D008875:Middle Aged; D012189:Retrospective Studies; D012529:Saudi Arabia; D012846:Singapore / Q000208:ethnology; D011795:Surveys and Questionnaires; D014195:Travel
chemical_list: D022401:Meningococcal Vaccines