A total of 147 people with asthma on inhaled corticosteroids ( British Thoracic Society Steps 2-5 ) , with a history of virus-associated exacerbations , were randomized to 14-day treatment with inhaled IFN - ( n = 72 ) or placebo ( n = 75 ) within 24 hours of developing cold symptoms and were assessed clinically , with relevant samples collected to assess virus infection and antiviral responses .