Fighting Weakens the Body

After a week, the immune system has typically defeated the flu, but the struggle has left its mark, meaning that symptoms such as swollen mucosa, joint pain, and fatigue might continue for up to two weeks.

The virus also makes the body an easy victim of other diseases. When the cells of the immune system are focused on one enemy – the flu – other viruses and bacteria might be overlooked. Secondary complications such as pneumonia could be lethal, but during the infection, the attacked cells might also overreact, secreting so many toxins that the result is a cytokine storm: an exaggerated immune response resembling a severe allergic reaction. The storm is believed to be the mechanism behind some of the worst epidemics such as the Spanish flu.