Final answer:
Several factors including a strong immune system, engaging in preventive behaviors like handwashing, possibly being vaccinated, and even luck with airflow and seating position in the theater, could explain why you didn't get the flu while others did.
Step-by-step explanation:
There can be several reasons why you did not develop influenza when exposed to the same environment as your friends who became ill. One possibility is that you have a stronger immune system, which can be bolstered by a healthy lifestyle, frequent handwashing, and possibly previous exposure to the flu virus, which might have provided some level of immunity. It is also possible that you engaged in behaviors that minimized your risk, such as avoiding close contact with the people who were coughing and sneezing, and refraining from touching your face after touching surfaces that may have been contaminated with the virus. Furthermore, if you were vaccinated against the flu, this could significantly reduce your chances of contracting the illness.
Another factor might be sheer luck; the exact positioning and airflow in the theater could have played a role in whether you inhaled enough of the virus to result in infection. It's also important to consider asymptomatic carriers - like the children who carried H. influenzae in the case study mentioned - you might have contracted the virus but didn't exhibit symptoms.
In summary, a combination of a healthy immune system, preventive behaviors, and possibly even luck could explain why you, unlike some of your friends, did not develop the flu after the movie-going experience during flu season.