A compartmental epidemic model is proposed to predict the Covid-19 virus spread. It considers: both detected and undetected infected populations, medical quarantine and social sequestration,  plus possible reinfection. The coefficients in the model are evaluated by fitting to empirical data for six US states: California, Louisiana, New Jersey, New York State, Texas, and Washington State . The evolution of Covid-19 is fairly similar among the states: contact and detection rates remain below 5\%; however,  variations are larger in death rate, recovery rate, and stay-at-home effect  . The results reveal that outbreaks may have been well underway in several states before first detected and that some western states might have seen more than one influx of the pandemic. For the majority of states the model's effective reproduction number is slightly above the critical value of one, indicating that Covid-19 will become endemic, spreading for more than two years. Should  stay-at-home orders be revoked , most states may experience oscillating yearly infections. Even if additional lockdowns are applied in Texas, and then released according to White House guidelines of 14 days of decreasing cases, a similar endemic situation may occur. Additionally, if lockdowns had been instituted one to three weeks sooner , the number of Covid-19 deaths in New York could have been significantly reduced, but surprisingly not in Texas (perhaps due to aversion to lockdown and absence of a decree).
A compartmental epidemic model is proposed to predict the Covid-19 virus spread. It considers: both detected and undetected infected populations, medical quarantine and social sequestration, release from sequestration, plus possible reinfection. The coefficients in the model are evaluated by fitting to empirical data for eight US states: Arizona, California, Florida, Illinois, Louisiana, New Jersey, New York State, and Texas. Together these states make up 43\% of the US population; some of these states appear to have handled their initial outbreaks well, while others appear to be emerging hotspots . The evolution of Covid-19 is fairly similar among the states: variations in contact and recovery rates remain below 5\%; however, not surprisingly, variations are larger in death rate, reinfection rate, stay-at-home effect , and release rate from sequestration . The results reveal that outbreaks may have been well underway in several states before first detected and that California might have seen more than one influx of the pandemic. Our projections based on the current situation indicate that Covid-19 will become endemic, spreading for more than two years. Should states fully relax stay-at-home orders , most states may experience a secondary peak in 2021. If lockdowns had been kept in place , the number of Covid-19 deaths so far could have been significantly lower in most states that opened up. Additionally, our model predicts that decreasing contact rate by 10\%, or increasing testing by approximately 15\%, or doubling lockdown compliance (from the current \sim 15\% to \sim 30\%) will eradicate infections in the state of Texas within a year. Extending our fits for all of the US states, we predict about 11 million total infections (including undetected), 8 million cumulative confirmed cases, and 630,000 cumulative deaths by November 1, 2020.
A
release from sequestration,
R
six
eight
R
California,
Arizona, California, Florida, Illinois,
R
Texas, and Washington State
and Texas. Together these states make up 43\% of the US population; some of these states appear to have handled their initial outbreaks well, while others appear to be emerging hotspots
R
contact and detection
variations in contact and recovery
A
not surprisingly,
R
recovery rate, and
reinfection rate,
A
, and release rate from sequestration
R
some western states
California
R
For the majority of states the model's effective reproduction number is slightly above the critical value of one, indicating
Our projections based on the current situation indicate
A
states fully relax
D
be revoked
R
oscillating yearly infections. Even if additional lockdowns are applied in Texas, and then released according to White House guidelines of 14 days of decreasing cases, a similar endemic situation may occur. Additionally, if
a secondary peak in 2021. If
R
instituted one to three weeks sooner
kept in place
R
in New York
so far
R
reduced, but surprisingly not in Texas (perhaps due to aversion to lockdown and absence of a decree).
lower in most states that opened up. Additionally, our model predicts that decreasing contact rate by 10\%, or increasing testing by approximately 15\%, or doubling lockdown compliance (from the current \sim 15\% to \sim 30\%) will eradicate infections in the state of Texas within a year. Extending our fits for all of the US states, we predict about 11 million total infections (including undetected), 8 million cumulative confirmed cases, and 630,000 cumulative deaths by November 1, 2020.