title: The weight of MMRV-related febrile convulsions among other clinical factors contributing to febrile convulsions in children.
abstract: BACKGROUND
  It was previously demonstrated that MMRV vaccine causes a higher rate of febrile convulsions (FC) compared to the MMR vaccine. Additional risk factors for FC include age, familial tendency, day care attendance, viral diseases, complications at birth and developmental delay.
  
  
  OBJECTIVE
  We evaluated the relative and attributable risk of FC for vaccinees' age, ethnicity, low birth weight, preterm birth and MMRV vaccination in 10-24 months old children.
  
  
  METHODS
  Data on medical history and vaccination were extracted from data warehouses of Clalit Health Services and Israel's Ministry of Health and linked on an individual record level for 90,294 MMR- and 8344 MMRV-vaccinees. A retrospective study design was used to reveal the risk factors associated with FC in study participants.
  
  
  RESULTS
  During the second week after immunization, an elevated relative risk of FC was demonstrated in MMRV-recipients (adjusted RR=2.16 (95%CI: 1.01; 4.64)). However, the cumulative incidence of FC during the entire 40-day observation period did not differ between the MMR and MMRV vaccinees. The MMRV-specific attributable risk of FC was not statistically significant at any point of observation period and was exceedingly low compared to other risk factors, equaling 5.3 FC cases per 10,000 vaccinees (95%CI: -1.4; 12.2).
  
  
  CONCLUSIONS
  Our findings demonstrate that MMRV-associated FC in 10-24 months old contributes very marginally to the overall rate of FC in this population.
  
  
  CONCLUSIONS
  Given the low number of MMRV-specific FC cases, their transient nature and the benefit of vaccination, the overall benefit-risk of the vaccine can be considered favourable. Nonetheless, the option of separate immunization with MMR+V should be offered to parents, in order to maintain sufficient vaccine uptake in the population.
authors: Department of Public Health, Ben-Gurion University of the Negev, Israel. Electronic address: nataliag@post.bgu.ac.il.
authors: Natalie
authors: N
authors: Gavrielov-Yusim
authors: Clalit Research Institute and Health Policy Planning Department, Chief Physician Office, Clalit Health Services, Israel.
authors: Moshe
authors: M
authors: Hoshen
authors: Clalit Research Institute and Health Policy Planning Department, Chief Physician Office, Clalit Health Services, Israel.
authors: Shepherd Roee
authors: SR
authors: Singer
authors: Department of Public Health, Ben-Gurion University of the Negev, Israel.
authors: Lily
authors: L
authors: Neumann
authors: Department of Public Health, Ben-Gurion University of the Negev, Israel; Clalit Research Institute and Health Policy Planning Department, Chief Physician Office, Clalit Health Services, Israel.
authors: Ran D
authors: RD
authors: Balicer
mesh_terms: D019433:Chickenpox Vaccine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007223:Infant; D007557:Israel / Q000453:epidemiology; D008297:Male; D022542:Measles-Mumps-Rubella Vaccine / Q000009:adverse effects*; D012189:Retrospective Studies; D012307:Risk Factors; D003294:Seizures, Febrile / Q000139:chemically induced* / Q000453:epidemiology; D014611:Vaccination / Q000009:adverse effects*; D017778:Vaccines, Combined / Q000009:adverse effects
chemical_list: D019433:Chickenpox Vaccine; D022542:Measles-Mumps-Rubella Vaccine; D017778:Vaccines, Combined; C050102:measles, mumps, rubella, varicella vaccine
keywords: Adverse event; Febrile convulsions; MMRV; Vaccination