  State government-mandated social distancing measures have helped to slow down
the growth of the COVID-19 pandemic in the United States. Current predictive
models of the development of COVID-19, especially after mitigation efforts, are
largely based on extrapolating the data from other countries. Since most states
enforced stay-at-home orders towards the end of March, their effect should be
reflected in the death and infection counts at the end of April. Using the data
available until April 25th, we investigate the change in the infection rate due
to the mitigation efforts, and project death and infection counts until
September, 2020, for some of the most heavily impacted states: New York, New
Jersey, Michigan, Massachusetts, Illinois and Louisiana. We find that with the
current mitigation efforts five of those six states reduce their reproduction
number to a value less than one, stopping the exponential growth of the
pandemic. We also projected different scenarios after the mitigation is
relaxed. Analysis for other states can be found at
https://covid19projection.org/.
