Within the world of HIV medicine, the concept of "test and treat" -- or rapid HIV testing and immediate treatment initiation -- is now an evidence-backed way to improve public health and reduce HIV transmission.
But does the same paradigm hold up for hepatitis C (HCV)?
With today's new generation of direct-acting antivirals (DAAs), researchers are slowly exploring whether a test-and-treat approach could work for certain highly vulnerable populations.
At IDWeek 2019, two presentations summarize current evidence for test-and-treat among HCV-positive pregnant women and men who have sex with men (MSM) -- two groups that have been labeled "key populations" by the Infectious Diseases Society of America (IDSA) and the American Association for the Study of Liver Diseases (AASLD).
Although early research on test-and-treat appears promising for these two groups, experts agree that more studies are needed.
In theory, all pregnant women considered "at risk" for HCV should be screened for infection. In practice, that isn't happening, explained Catherine Chappell, M.D., M.Sc., assistant professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the University of Pittsburgh Medical Center (UPMC).
In fact, a 2016 study from the UPMC Magee-Womens Hospital, where Chappell practices, found that only about three-fourths of women with reported opioid use disorder were screened for hepatitis C during their pregnancy visits. The majority of women who were screened tested positive for HCV antibodies.
Chappell wondered if -- with the advent of DAAs -- there might be an important opportunity to cure HCV among women who are already engaged in medical care. Because the major DAA studies excluded pregnant women, Chappell and her colleagues first sought to determine if DAAs are even safe to use during pregnancy.
She launched a phase 1 study of ledipasvir/sofosbuvir (Harvoni) among pregnant women with HCV infection. They enrolled women who planned to deliver at Magee-Womens Hospital who did not have comorbid infections or other serious illnesses.
Nine women were ultimately included in the study. They were all white, 31 years old on average, and most had acquired HCV through prior injection drug use. Doctors initiated a 12-week course of therapy in the last trimester of pregnancy, and they followed the women and infants for one year after delivery.
"There was no significant [pharmacokinetic] change in pregnant versus non-pregnant women," said Chappell. And, although not all of the mothers were cured of HCV at the time of delivery, "all the infants have had negative HCV viral loads during follow-up."
Many more studies will be needed to determine if test-and-treat is a good strategy among HCV-positive pregnant women, but Chappell's early research indicates it's a strategy worth exploring.
Before the advent of DAAs, there wasn't much doctors could do to treat pregnant women, or to prevent HCV transmission to children. But if studies continue to show DAA treatment is safe during pregnancy, prenatal visits might become a new opportunity to test and treat for HCV.
Men Who Have Sex with Men (MSM)
Starting in 2000, HCV began appearing among HIV-positive MSM. In recent years, several studies have indicated that HCV may also now be "bridging" to HIV-negative MSM.
The good news is that large clinical studies such as SWIFT-C show it's perfectly safe to treat and cure HCV among HIV-positive people.
Typically, HCV patients are treated years after initial exposure, after the "acute" stage of infection has already passed and there is no chance the patient will spontaneously clear the infection.
But according to Anne Boerekamps, M.D., an infectious disease specialist at Erasmus University Medical Center in Rotterdam, Netherlands, it could be cost-effective to treat high-risk MSM during the acute stage of HCV infection.
"The concept of treating acute hepatitis C is not only beneficial for preventing transmission but could also help to reduce cost of hepatitis C treatment," she said, speaking at IDWeek.
But would it actually work? In 2017, Boerekamps and her colleagues published a study that found that giving HIV-positive Dutch MSM unrestricted access to DAAs resulted in a 51% decrease in acute HCV infections.
However, a worrying study from France -- which implemented a similar HCV treatment policy -- saw an increasing incidence of HCV infection among HIV-positive MSM between 2012 and 2016.
In addition, a subsequent study from London found that although HCV rates fell overall, re-infection rates increased among a small cohort of HIV-positive MSM. The troubling reinfection rates among MSM in France and London indicate that more research is needed to determine if test-and-treat is a good strategy for all MSM with HIV.
Current data suggest that, "for some scenarios, treatment as prevention will work," said Boerekamps. But overall, "there is still a lack of evidence on how to treat these populations."