Figure 2.

Characteristics of different age groups. (A) The heatmap show the prevalence of the symptoms in the investigated age groups. The columns and rows represent the different age groups and symptoms, respectively. (B) The heatmap show the prevalence of the complications in the different age groups. (C) The biplot from principal component analysis revealing the relationship between the symptoms, complications, and different age groups. Arrows indicate symptoms and complications, pointing to age groups in two‐dimensional space. Arrow length and direction are informative: longer arrows are more specific, whereas shorter arrows indicate more general symptoms and complications. Symptoms and complications that are close to each other at right angles are not correlated. Angles smaller than right angles indicate a positive correlation, whereas angles larger than right angles indicate a negative correlation.