| There is no universally accepted method for forecasting
an epidemic similar to cohort component technique in demography.
The UNAIDS reference group suggested to project
the HIV/AIDS epidemic in the countries with a concentrated epidemic by
forecasting changes in the size of risk groups. The population groups at
greatest risk for HIV are identified, and their size is estimated. Then
an assumption is made about a possible HIV prevalence among the groups
as to years and about the time when such prevalence may be at the highest.
And, finally, assumptions are made about the degree of infection transmission
to the rest of the population. Theoretically, such a pattern appears to
look well, but in practice (as has been stated above) it turns out to be
an extremely difficult task to make quantitative estimates of covert population
groups like injection drug users (IDUs), commercial sex workers (CSWs)
and men having sex with men (MSMs). Besides, HIV prevalence in Russia can
be estimated on the basis of direct observations (registration of HIV cases).
For this reason we used an approach based on the
HIV prevalence among the adult population, while other determinants are
just the functions of this variable. The future parameters of the epidemic
and its demographic impact were determined by means of Spectrum. Since
the Spectrum package inadequately works with Russian data (in particular,
data on mortality), the output of the package was used as input variables
for population projections software adopted by the Center for Demography
and Human Ecology. Therefore, the HIV-epidemic forecast made by means of
the Spectrum package was combined with the population projections.
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