In this research, we are interested in predicting the epidemic peak outbreak of the Coronavirus in South
Africa, Turkey, and Brazil. Until now, there is no known safe treatment, hence the immunity system of the
individual has a crucial role in recovering from this contagious disease. In general, the aged individuals
probably have the highest rate of mortality due to COVID-19. It is well known that this immunity system
can be affected by the age of the individual, so it is wise to consider an age-structured SEIR system to
model Coronavirus transmission. For the COVID-19 epidemic, the individuals in the incubation stage are
capable of infecting the susceptible individuals. All the mentioned points are regarded in building the
responsible predictive mathematical model. The investigated model allows us to predict the spread of
COID-19 in South Africa, Turkey, and Brazil. The epidemic peak outbreak in these countries is considered,
and the estimated time of the end of infection is regarded by the help of some numerical simulations.
Further, the influence of the isolation of the infected persons on the spread of COVID-19 disease is investigated.