  We construct an agent-based SEIR model to simulate COVID-19 spread at a
16000-student mostly non-residential urban university during the Fall 2021
Semester. We find that mRNA vaccine coverage above 80% makes it possible to
safely reopen to in-person instruction. If vaccine coverage is 100%, then our
model indicates that facemask use is not necessary. Our simulations with
vaccine coverage below 70% exhibit a right-skew for total infections over the
semester, which suggests that high levels of infection are not exceedingly rare
with campus social connections the main transmission route. Less effective
vaccines or incidence of new variants may require additional intervention such
as screening testing to reopen safely.
