كارآيي واكسن آنفلونزا در پيشگيري ازبيماري شبه آنفلوانزا در زايرين ايراني حج سال 1382

Efficacy of Influenza Vaccine on Influenza Like Illness Among Iranian Pilgrims in Hajj 2004

Background: About 1.9 millions persons from approximately 140 different countries and 94 thousands from Iran come together in Saudi Arabia for the Hajj each year. Regarding to high incidence of respiratory infections symptoms; the serious problems of pilgrims and Hajj medical organizations; in recent years prevention of these symptoms for Hajj programming managers is essential. We performed this study to determine effect of influenza vaccination on incidence of influenza like illness and other respiratory tract infection symptoms among Iranian pilgrims in Hajj 2004. Materials and methods: This research was a cohort study and performed on 406 pilgrims (vaccinated =203 & control =203) of six caravans from Tehran, Qom, Semnan, Mahdishahr and Shahryar. In Hajj period daily, symptoms and physical examination findings of pilgrims phone weekly for one month after comeback to Iran. Data was analyzed by t, mann-withney and chi-square tests. Results: Mean duration of cough, sore throat and nasal congestion in vaccinated group reduced 1.2, 0.5 and 0.4 day respectively. Mean rate of cough incidence reduced from 1.4 to 1.3, headache incidence reduced from 0.8 to 0.7, rhinorrhea incidence from 1.2 to 1, nasal congestion incidence from 1 to 0.8, but only nasal congestion incidence reduction was statistically significant (p<0.02). Cough, sore throat, headache, and nasal congestion severity in vaccinated group were approximately 3 to 7 percent lower than unvaccinated group and these symptoms incidences in vaccinated group were 3 to 9 percent lower than unvaccinated group but only nasal congestion incidence reduction was statistically significant (p<0.,05). Finally Influenza like illness symptoms preventive efficacy of influenza vaccine was 20%. Conclusion Influenza vaccine efficacy to prevent influenza like illness among Iranian pilgrims in Hajj 2004 was low. it could be due to i-04 influenza vaccine. Regarding to socioeconomics aspects, we recommend only high risk groups of pilgrims should be vaccinated.