Every year, we are reminded both online and on the evening news of the deadly effects of the flu. There's no doubt that influenza is a killer. The Centers for Disease Control estimates that 80,000 Americans died from the flu in 2017. But how can a simple case of the flu that many people recover from in a week or two be so deadly to others? Doctors who study the body's immune response cite three reasons. First, when the immune system is taxed, there is a good chance of co-infection with another germ-usually a bacterium, such as strep. Second, the flu can easily aggravate existing conditions such as heart disease and asthma. Third is the so-called cytokine storm. This is an overproduction of immune cells and their activating compounds (cytokines) in the lungs. The resulting lung inflammation and fluid buildup can lead to severe lung distress and can open the door to other diseases such as bacterial pneumonia.
What is a key reason the flu can be deadly to some people?

Question

Quizplus · Accepted Answer

The passage states that "when the immune system is taxed, there is a good chance of co-infection with another germ."
Most people aren't aware of its dangers until too late is incorrect. The passage does not mention that people aren't aware of the disease until it's too late. 
It is the main cause of serious heart disease is incorrect. The passage does not say that the flu virus causes heart disease. Rather, it states that existing conditions like heart disease are aggravated-made worse-by the flu. 
The flu virus is responsible for causing serious illnesses such as strep is incorrect. The flu virus does not cause strep-a bacterium does.

Every Year, We Are Reminded Both Online and on the Evening