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The COVID-19 pandemic has plagued the world for months. The U.S. has taken measures to counter it. On a daily basis, newly conﬁrmed cases have been reported. In the early days, these numbers showed an increasing trend. Recently, the numbers have been generally ﬂattened out. This report tries to estimate the hidden number of currently alive infections in the population by using the conﬁrmed cases. A major result indicates an existing infections estimate at about 10-50 times the daily conﬁrmed new cases, with the stringent social distancing policy tipping to the upper end of this range. It clariﬁes the relationship between the infection rate and the test rate to put the epidemic under control, which says that the test rate shall keep up at the same pace as infection rate to prevent an outbreak. This relationship is meaningful in the wake of business re-opening in the U.S. and the world. The report also reveals the connections of all the measures taken to the epidemic spread. A stratiﬁed sampling method is proposed to add to the current tool kits of epidemic control. Again, this report is a summary of some straight observations and thoughts, not through a thorough study backed with ﬁeld data. The results appear obvious and suitable for general education to interested policymakers and the public.