In December 2001 Aviron was acquired by SBIR firm MedImmune - itself having been an SBIR involved firm that later went on to be acquired by AstraZeneca. Aviron was a biopharmaceutical company focused on prevention of disease through devlopment of cost-effective vaccines to justify their use in immunization programs targeting the general population. Aviron's vaccine programs are based on both classical live virus attenuation techniques and the Company's proprietary genetic engineering technologies. The Company's lead product, an influenza vaccine delivered as an intranasal spray (FluMist), has been shown to provide a high protection rate against influenza with minimal adverse effects. Aviron is developing this live vaccine for widespread use in children, healthy adults and high-risk adults. The Company is also developing potential vaccines for Parainfluenza Virus Type 3 (PIV-3), Epstein-Barr Virus (EBV), Congenital Cytomegalovirus (CMV) infection, Respiratory Syncytial Virus (RSV), and Herpes Simplex Virus Type 2 (HSV-2).