 The primary endpoint will be based on the comparison of cumulative lower respiratory tract symptoms scores CLRTS in the asthmatic subjects treated with omalizumab compared to those treated with placebo over the first 4 days of acute infection. Diary cards will be scored daily for cough, shortness of breath, chest discomfort and wheezing using a modification of the Jackson criteria. To participate in this study, subjects must live within 90 minutes by car from the University of Virginia. 