OBJECTIVETo study the preventive effect of recombinant human interferon alpha-2b for nasal spray against SARS and other common respiratory viral infections by serum-epidemiological method.

METHODSA randomized, placebo-controlled, double-blind field trial study in populations with 14,391 persons from SARS prevalent cities or provinces in China during May-Jun, 2003 and Dec-Apr, 2004. Interferon alpha-2b was given twice per day, once 9 x 10(5) IU by nasal spray for 5 days. Serum samples were taken at 15 days after last administration. Serological tests included SARS IgG antibody and IgM antibodies against influenza B, parainfluenza virus types 1-3, adenovirus type 3, 7 and respiratory syncytial virus by using commercial ELISA kits.

RESULTSNo statistically significant difference in serum SARS IgG antibody positive rate was found between the interferon and control groups among 2,757 serum samples. On the other hand, after using interferon, all four respiratory viruses (parainfluenza virus types 1-3 influenza B, adenovirus types 3, 7 and respiratory syncytial virus) in interferon group had lower IgM antibody positive rates than those in control group. Among them there were statistically significant differences between the interferon and control groups for parainfluenza virus, influenza B and adenovirus. The preventive efficacy of interferon against four respiratory viruses was different, from high to low, the rank was Flu B (66.76%), parainfluenza types 1-3 (66.75%), RSV (39.61%) and adenovirus (32.86%). The average preventive efficacy was 50.27%.

CONCLUSIONThe recombinant human interferon alpha-2b for nasal spray could decrease the rates of common respiratory viruses infection in the selected population.