December 16, 2015
Researchers at Yale University and the pharmaceutical company Merck have developed a sophisticated computer model of the hepatitis C virus (HCV) epidemic in the United States. The Yale team estimated that there are up to five million people living with HCV in the U.S. and about 100,000 are treated each year.
Using high-performance computers, the research team found that if the number of HCV-infected people in the U.S. who received treatment each year were to increase four-fold, major positive impacts on the epidemic would occur, including the following:
Furthermore, by increasing opportunities for the offer of HCV testing followed by swift linkage to care and treatment, the pool of infected people would significantly diminish over time. Additional projections from the Yale analysis as well as from teams at other universities are presented later in this CATIE News bulletin. All of these projections and analyses have underscored the issue of drug pricing as an important barrier to the timely eradication of the HCV epidemic.
Researchers put an enormous volume of information into their model, including data collected between 1992 to 2014 from many key studies about HCV testing and, when possible, treatment. An important aspect of the Yale model is that it assumed that future use of DAAs would result in cure rates of about 95%. For simplicity, we have rounded off figures in our report.
Based on multiple scenarios and calculations, the Yale team detailed how many people would need to be treated each year so that the population of HCV-infected people could eventually decrease by 80%:
By intensifying opportunities for treatment, major reductions in cases of cirrhosis could occur under the following scenario:
Other research teams have found that many people who are infected with HCV do not know their infection status. Therefore, the Yale researchers underscore the importance of offering HCV testing to help uncover this infection and get people linked to care and treatment. The Yale team said that "without expansion of HCV screening at least 463,000 [undiagnosed cases of HCV] would remain untreated through [the year] 2040. ..." Specifically, the researchers stated that if rates of HCV testing remain where they are now, new cases of HCV infection will only "be reduced, at most, by 15%."
The researchers also suggest that HCV testing be offered in the emergency rooms of hospitals. Studies have found that this can be effective in helping to uncover HCV infection and linking people to care and treatment.
In the U.S. today, according to the Yale researchers, "new [HCV] infections occur principally among [people who inject street drugs] and therefore will not be appreciably reduced without increasing more [opportunities offering testing, care and treatment] for this vulnerable population."
The Yale team estimates that presently only about 4% of people who inject street drugs get tested for HCV. The team stated that if this rate of testing does not increase, large declines in the rate of new infections will not occur until 2040.
The researchers said that to eventually reduce cases of new HCV infections in this population by 90% would require "universal [HCV] screening and at least 20% [of new cases of HCV would require treatment each year]."
Alternatively, the team found that if 20% of people who inject street drugs are screened for HCV every year and 30% of newly diagnosed HCV cases are offered treatment each year, eventually "at least 90%" of people who inject street drugs would no longer have HCV.
The team underscores the importance of providing medical care "in a nonjudgmental setting" for people who inject street drugs.
To eliminate the HCV epidemic, the team stated that programs will need to "incorporate enhanced HCV [testing] and treatment with needle and syringe exchange programs," as these help to reduce the spread of HCV. Furthermore, the researchers said that "opiate substitution therapy" will need to accompany such programs in order to assist people who are trying to recover from addiction. All of these efforts focused on preventing HCV infection (and in some cases re-infection) are necessary because a highly effective vaccine to prevent HCV is unlikely to become available in the foreseeable future.
Researchers who construct models of the HCV epidemic need to bear in mind that, in addition to addiction, the psychosocial drivers that lead to HCV infection -- including anxiety, depression and other mental health issues -- need to be addressed. For some people with HCV, this infection is merely one on a list of issues with which they grapple. Therefore, psychosocial support is an important part of recovery from HCV and avoiding re-infection in the future.
The Yale researchers pointed to other challenges involved in tackling the HCV epidemic, such as the following:
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