To further illustrate the systemic features' ability to either rule in or rule out COVID‐19 disease or COVID‐19 pneumonia, we constructed dumbbell plots showing pre‐ and post‐test probabilities for each feature in each study (Figure 16). For each test, we have plotted the pre‐test probability, which is the prevalence of COVID‐19 disease (blue dot). Probability then changes depending on a positive test result (red dot marked +) or a negative test result (green dot marked ‐). The plot shows that fever, for example, increases the probability of COVID‐19 in two studies (Ai 2020a; Rentsch 2020), makes little to no difference in five studies (Feng 2020; Liang 2020; Peng 2020; Song 2020; Zhu 2020), and decreases the probability of COVID‐19 in two studies (Cheng 2020a; Tolia 2020).