A case-control study of influenza vaccine effectiveness among Malaysian pilgrims attending the Haj in Saudi Arabia.
OBJECTIVE
To determine influenza vaccine effectiveness against clinically defined influenza-like illness among Malaysian pilgrims attending the Haj in Saudi Arabia.


METHODS
During February and March 2000, the authors conducted an unmatched case-control study. Case patients were identified at one of five hotel clinics, while controls were residents of these hotels who had not attended a clinic.


RESULTS
Among 820 case patients--84% of whom had received antibiotics--and 600 controls, the adjusted vaccine effectiveness against clinic visits for influenza-like illness was 77% (95% confidence interval: 69, 83), and that against receipt of antibiotics was 66% (95% confidence interval, 54, 75). The vaccine did not prevent clinic visits for non-influenza-like upper respiratory tract illness (adjusted vaccine effectiveness, 20%; 95% confidence interval: -24, 49).


CONCLUSIONS
Influenza vaccine was effective in preventing clinic visits for influenza-like illness and antibiotic use. Pilgrims traveling to the Haj in Saudi Arabia should consider influenza vaccination use.
Mustafa
Amal Nasir
AN
Institute for Medical Research, Kuala Lumpur, Malaysia.
Gessner
Bradford D
BD
Ismail
Raman
R
Yusoff
Ahmad Faudzi
AF
Abdullah
Nasuruddin
N
Ishak
Ilina
I
Abdullah
Norazmi
N
Merican
Mohd Ismail
MI
D016022:Case-Control Studies; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000276:immunology; D009981:Influenza B virus / Q000276:immunology; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control* / Q000821:virology; D007514:Islam; D008296:Malaysia; D008297:Male; D008875:Middle Aged; D012529:Saudi Arabia; D014195:Travel; D014611:Vaccination
D007252:Influenza Vaccines