  In this article, we investigate the importance of demographic and contact
patterns in determining the spread of COVID-19 and to the effectiveness of
social distancing policies. We investigate these questions proposing an
augmented epidemiological model with an age-structured model, with the
population divided into susceptible (S), exposed (E), infected and asymptomatic
(A), hospitalized (H), infected and symptomatic (I), and recovered individuals
(R), to simulate COVID-19 dissemination. The simulations were carried out using
six combinations of four types of isolation policies (work restrictions,
isolation of the elderly, community distancing and school closures) and four
representative fictitious countries generated over alternative demographic
transition stage patterns (aged developed, developed, developing and least
developed countries). We concluded that the basic reproduction number depends
on the age profile and the contact patterns. The aged developed country had the
lowest basic reproduction number ($R0=1.74$) due to the low contact rate among
individuals, followed by the least developed country ($R0=2.00$), the
developing country ($R0=2.43$) and the developed country ($R0=2.64$). Because
of these differences in the basic reproduction numbers, the same intervention
policies had higher efficiencies in the aged and least developed countries. Of
all intervention policies, the reduction in work contacts and community
distancing were the ones which produced the highest decrease in the $R0$ value,
prevalence, maximum hospitalization demand and fatality rate. The isolation of
the elderly was more effective in the developed and aged developed countries.
The school closure was the less effective intervention policy, though its
effects were not negligible in the least developed and developing countries.
