Abstract
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.