Figure 2. Analysis of probable primary cases of coronavirus disease (COVID-19) among 22 clusters in communities, Japan. A) Age ranges of probable primary COVID-19 cases in clusters. Age distribution among all COVID-19 cases in Japan is provided as reference. B) Proportions of symptoms among probable primary cases of COVID-19 clusters at transmission (n = 16) and among at laboratory confirmed diagnosis (n = 22). 1, Asymptomatic; 2, fever; 3, fatigue; 4, cough; 5, sore throat; 6, headache; 7, arthralgia or myalgia; 8, runny nose; 9, diarrhea; 10, difficulty breathing. C) Distribution of probable primary cases of COVID-19 clusters by time of transmission compared with illness onset by age groups (n = 16). Six cases were excluded because the time of transmission was undetermined.