"the incidence of influenza like illness and determination of the efficacy of flu vaccine in iranian pilgrims during hajj pilgrimage"

every year, millions of moslems depart to saudi arabia from more than one hundred countries around the world for paying to hajj precept. high percentages of these pilgrims suffer from an influenza-like illness (ili). this study was designed and conducted on 32370 iranian pilgrims (36% of total number of iranian pilgrims) to evaluate the incidence of the illness and determination of influenza vaccine’s efficacy to prevent it. a total of 3465 individuals, 10.7% of under studied population, had vaccinated themselves voluntarily against the influenza and the rest were not vaccinated. as a whole, 70% of the studied population suffered from ili. in this study, the incidence of illness among those vaccinated was about 56% and among those not vaccinated about 72%; the difference was significant (p < 0.001), with odds ratio (od) = 0.50 and (1 - od) = 0.50; thus the efficacy of the vaccine in this study was estimated to be 50% and it was efficient in reducing the cases of ili. we recommend administration of the influenza vaccine to iranian pilgrims one month before departure to saudi arabia for hajj pilgrimage.