RESUMEN
This paper uses commonly available prevalence estimates to bound future incidence. The bounds rely on restricting the fraction of contacts between individuals of different infection statuses. It is argued that these bounds can be further tightened by restrictions of economic models of infectious disease that imply that uninfected individuals have larger incentives to avoid matching with infected individuals than do the infected individuals themselves. This implies that incidence predictions from canonical models of infectious disease are worst-case upper bounds, with the degree to which they overestimate new cases being monotonically related to this type of infection-dependent matching. Evidence in support of the economic type of infection-dependent matching is presented, by using data on the joint distribution of partners' HIV statuses in a random sample of couples from San Francisco in 1988-1989.
Asunto(s)
Enfermedades Transmisibles/transmisión , Enfermedades Transmisibles/economía , Enfermedades Transmisibles/epidemiología , Femenino , Infecciones por VIH/economía , Infecciones por VIH/epidemiología , Infecciones por VIH/transmisión , Humanos , Masculino , Matemática , Modelos Biológicos , Modelos EconómicosRESUMEN
Using data from The San Francisco Home Health Study (SFHHS), this paper analyzes the degree to which the incentives to avoid HIV infection result in infection-dependent (assortative) matching patterns based on HIV status. The incidence implications induced by such matching are compared to infection independent matching, an implicit assumption in canonical models within epidemiology. We estimate that an HIV-positive individual is more than twice as likely as an HIV-negative individual to have an HIV-positive partner, and that this results in a decrease in HIV incidence of about one-third compared to the predictions implied by standard epidemiological models.
Asunto(s)
Infecciones por VIH/epidemiología , Distribución de Chi-Cuadrado , Susceptibilidad a Enfermedades , Infecciones por VIH/prevención & control , Infecciones por VIH/transmisión , Seronegatividad para VIH , Seropositividad para VIH , Encuestas Epidemiológicas , Homosexualidad Masculina , Humanos , Incidencia , Masculino , Modelos Estadísticos , San Francisco/epidemiología , Parejas SexualesRESUMEN
OBJECTIVE: To evaluate whether immunization against a vaccine-preventable disease is sought to avoid the naturally occurring disease itself, we hypothesized that the rate of "on-time" measles immunization would increase during an epidemic of that disease. If such an effect occurred, we wondered whether it would have an impact on on-time administration of other recommended immunizations. DESIGN: Retrospective evaluation of immunization rates of children at their second birthday with the use of computerized health records of children entering kindergarten in an 8-year interval spanning the onset of epidemic measles in Chicago, Ill, in 1989 and 1990. SETTING: Children entering Chicago public schools. MAIN OUTCOME MEASURES: Rates of receipt of measles-containing vaccine (MCV), 1 to 4 doses of a diptheria toxoid-tetanus toxoid-pertussis (DTP) or diphtheria toxoid-tetanus toxoid (DT) vaccine, 1 to 3 doses of oral or inactivated polio vaccine (OPV/IPV), and the full series of these vaccines (4:3:1) that are required to be "up-to-date" by the second birthday. RESULTS: The rate of on-time MCV receipt increased from 56% to 58% in the years prior to 70% during the epidemic (1989 and 1990). A similar increase did not occur to DTP/DT 4 or OPV/IPV 3. Moreover, among older children delayed in MCV receipt, evidence of catch-up immunization also occurred during the epidemic years; similar catch-up for delayed DTP/DT 4 or OPV/IPV 3 immunization did not occur. CONCLUSIONS: Dramatic increases in one-time and catch-up MCV receipt occurred during the Chicago measles epidemic of 1989 and 1990. The lack of similar increases in DTP/DT 4 and OPV/IPV 3 suggests MCV receipt was not associated with receipt of other recommended immunizations during that time.