Assessment of effectiveness of Vaxigrip.

In order to assess the effectiveness of Vaxigrip in 1996-1997, we chose 1356 people in the Chinese Army, who had not recently had influenza and who were divided into an injection group and a control group. The injection group consisted of 80 children aged 3-6 years, 363 adults aged 18-59 years and 235 people over 60 years of age. The control group consisted of 88 children aged 3-6, 372 adults aged 18-59 and 218 people over 60. They were observed from the 21st day to the 6th month after Vaxigrip administration. Each person was requested to report having a body temperature over 38.5 degrees C, headache, myalgia or arthalgia, cough, pharyngodynia or nasal obstruction. Fever due to other causes was not included in the influenza symptoms. We counted the symptoms of influenza and common cold only once during the observation period. Our final finding was that the incidence rates of the influenza and common cold symptoms were reduced by 84.8% in children, 74.0% in adults and 68.6% in elderly people. In comparison with the control group, the incidence rate of influenza-like symptoms was reduced by 71.1% in the injection group, and the incidence rate of common cold symptoms in the injection group was lower than that in the control group. There was no large difference by age. The incidence rate of symptoms of upper respiratory tract infection in the injection group was 47.5% lower than that in the control group. Our findings are basically the same as those in other countries.