Although a vaccine for hepatitis C virus (HCV) remains elusive, new direct-acting antiviral (DAA) drugs can cure HCV effectively and conveniently. The latest DAA, Epclusa, can cure 95-99% of chronic hepatitis C regardless of genotype (e.g. see here). So if DAA drugs become universally available, will HCV be the first virus eradicated solely by drugs?

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    $\begingroup$ It is not the answer you are looking for, but for the fun of it: Yes, simplest situation being to eradicate all the vectors of the virus = eradication of the virus itself. :) $\endgroup$
    – Dart Feld
    Dec 21 '16 at 19:20

Is it feasible to eradicate a virus without vaccines?

It is possible? I would say yes. But feasible... I think not. Consider this, once vaccinated, a person is usually immune to the virus. And you only need the vaccine to take hold, for an individual to acquire life time immunity. However with drug treatment... even once the treatment succeeds, the person can be reinfected. And you will have come back with drug treatment again.

Given the difficult in vaccination campaigns (ie polio) to eradicate the last reserved of a virus... I think a similar drug based campaign would a lot more difficult. There is no herd immunity to prevent the virus from reinfecting the wider population when it leaves its strong holds.

  • $\begingroup$ You're right. Chronic hepatitis C doesn't confer any protective immunity, and those cured are still susceptible to reinfection. $\endgroup$
    – Ballistics
    Dec 22 '16 at 3:35
  • $\begingroup$ Herd immunity is a good point. I haven't thought of it. $\endgroup$
    – Ballistics
    Dec 22 '16 at 3:36
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    $\begingroup$ I would also add that outbreaks of measles when herd immunity breaks down show how easy it is for a virus to breakout. $\endgroup$
    – JayCkat
    Dec 22 '16 at 4:01

To the question I would say certainly yes, since the only viruses that have been eradicated (to my knowledge) are smallpox and rinderpest, both via vaccine campaigns (as well as the usual tools of quarantine/isolation).

Note: I did not mean to suggest that "if drugs are widely available they will definitely eradicate HCV". I interpreted the question as "if HCV is eradicated by DAA, will this be the first disease eradicated by drugs?"

Vaccines are typically used as prophylactic treatments, i.e. they are applied before an individual gets infected. Drugs can also be applied prophylactically (e.g. antiretroviral drugs against HIV), and vaccines can also be used post-infection, e.g. for rabies. In order for a cure (i.e., a treatment that is applied after an individual becomes infected) to eradicate disease, it must be applied soon after enough infection that it cuts down the infection period sufficiently to reduce the average number of secondary infections per infected person below 1. Analogously, when prophylactic treatments are given by age, as in the case of vaccines for childhood diseases, they must be administered to children young enough that most of them will not already have been naturally infected [and passed the virus on to others].

  • $\begingroup$ I think it is interesting to see how it goes. For HBV, we have vaccine but not cure, while for HCV we have cure but not vaccine. We can compare which is more efficient at shrinking the reservoir. $\endgroup$
    – Ballistics
    Dec 21 '16 at 17:52
  • $\begingroup$ My guess is that vaccines are more efficient at eradicating acute diseases(smallpox, polio, measles) because you can hardly have those infected get treated before they can transmit the disease. While for persistent infections(HIV, HCV, HBV) a cure may be more efficient. Because it takes long time for infected people to die out. $\endgroup$
    – Ballistics
    Dec 21 '16 at 17:55
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    $\begingroup$ Due to the long time people can be infected with no or almost no symptoms, I doubt that. A vaccination is much more reliable here. $\endgroup$
    – Chris
    Dec 21 '16 at 19:15
  • $\begingroup$ One could certainly evaluate all of this using a simple model. To know the cure rate, you'd need to know (1) the untreated R0 of the disease; (2) how much of the force of infection is mitigated by the cure [i.e., we need to know the infectious period, how much of it is asymptomatic, and the rate of cure administration - expected time from appearance of symptoms to cure] $\endgroup$
    – Ben Bolker
    Dec 21 '16 at 19:21

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