  In this note we estimate herd immunity levels for the Covid-19 epidemic using
a standard SEIR system that models the disease dynamics in homogeneous
populations. The results obtained are indicative of values between 80% and 90%
for unprotected, fully susceptible populations. Basic protective measures such
as hand hygiene and mask wearing may be effective to lower herd immunity levels
down to values between 50% and 60% of the total population.
