A real-time test for four common respiratory viruses has been approved by the U.S. Food and Drug Administration. The ProFlu+ test provides results within as few as three hours. Other respiratory virus tests are fast but not as accurate or are accurate but not as fast, the FDA said. The ProFlu+ test can analyze a single sample for influenza A virus, influenza B virus, and respiratory syncytial virus A and B (RSV). These viruses can cause influenza, pneumonia and an infection of the airways called bronchiolitis. All the viruses are leading causes of lower respiratory tract infections.