title: Changes in the prevalence of influenza-like illness and influenza vaccine uptake among Hajj pilgrims: A 10-year retrospective analysis of data.
abstract: BACKGROUND
  Influenza is an important health hazard among Hajj pilgrims. For the last ten years, pilgrims are being recommended to take influenza vaccine before attending Hajj. Vaccination coverage has increased in recent years, but whether there has been any change in the prevalence of influenza-like illness (ILI) is not known. In this analysis, we examined the changes in the rate of ILI against seasonal influenza vaccine uptake among Hajj pilgrims over the last decade.
  
  
  METHODS
  Data for this analysis is a synthesis of raw and published data from eleven Hajj seasons between 2005 and 214. For seven Hajj seasons the data were obtained from studies involving pilgrims of UK, Saudi Arabia and Australia; and for the remaining four Hajj seasons data were abstracted from published studies involving pilgrims from multiple countries. The data from both sources were synthesised to estimate the relative risk (RR) of acquisition of ILI in vaccinated versus unvaccinated pilgrims.
  
  
  RESULTS
  The pooled sample size of the included studies was 33,213 with most pilgrims being in the age band of 40-60 years (range: 0.5 to 95 years) and a male to female ratio of 1.6. The pilgrims originated, in order of frequency, from Iran, Australia, France, UK, Saudi Arabia, Indonesia, India, Algeria, Ivory Coast, Nigeria, Somalia, Turkey, Syria, Sierra Leone and USA. Except for one year (2008), data from individual years did not demonstrate a noticeable change in the rate of ILI against influenza vaccine coverage, however the combined data from all studies suggest that the prevalence of ILI decreased among Hajj pilgrims as the vaccine coverage increased over the last decade (RR 0.2, P<0.01).
  
  
  CONCLUSIONS
  This analysis suggests that influenza vaccine might be beneficial for Hajj pilgrims. However, controlled trials aided by molecular diagnostic tools could confirm whether such an effect is real or ostensible.
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia; Department of Family and Community Medicine, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia. Electronic address: malfelali@kau.edu.sa.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Alfelali
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia; King Abdullah Medical City, Makkah, Saudi Arabia.
authors.forename: Osamah
authors.initials: O
authors.lastname: Barasheed
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Tashani
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia.
authors.forename: Mohammad Irfan
authors.initials: MI
authors.lastname: Azeem
authors.affiliation: Al Maha Children Unit, Hamad Medical Corporation, Doha, Qatar.
authors.forename: Haitham
authors.initials: H
authors.lastname: El Bashir
authors.affiliation: Ministry of Health, and College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.
authors.forename: Ziad A
authors.initials: ZA
authors.lastname: Memish
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia.
authors.forename: Leon
authors.initials: L
authors.lastname: Heron
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, Australia.
authors.forename: Gulam
authors.initials: G
authors.lastname: Khandaker
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Booy
authors.affiliation: National Centre for Immunisation Research and Surveillance (NCIRS), The Children's Hospital at Westmead, and the Discipline of Paediatrics and Child Health, Sydney Medical School, University of Sydney, NSW, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, Sydney, Australia.
authors.forename: Harunor
authors.initials: H
authors.lastname: Rashid
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control*; D007514:Islam; D008297:Male; D015201:Meta-Analysis as Topic; D008875:Middle Aged; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000517:prevention & control*; D012189:Retrospective Studies; D012306:Risk; D012529:Saudi Arabia / Q000453:epidemiology; D013997:Time Factors; D014195:Travel; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
chemical_list: D007252:Influenza Vaccines
keywords: Hajj; Influenza; Influenza-like illness; Mass gathering; Travel; Vaccine