The study describes an experiment in which patients with the flu spent whole days in the same room with healthy volunteers. Despite long-term and close contact, the flu virus did not spread to healthy participants. The researchers found that limited coughing in sick people helped keep the amount of virus in the air low. An important factor was also the well-mixed indoor air, which reduced the concentration of the virus in the room. The authors of the paper report that middle-aged adults are less likely to catch the flu than younger people, which may have contributed to the results. In conclusion, the article emphasizes the importance of good ventilation, air movement and wearing masks as key measures against the spread of infections.