Two unrelated viruses that happen to specialise in the same organ cause most of the world's liver cirrhosis and most of its liver cancer. An analysis across eleven WHO regions attributed 57 percent of cirrhosis to hepatitis B (30 percent) or hepatitis C (27 percent), and 78 percent of hepatocellular carcinoma to hepatitis B (53 percent) or hepatitis C (25 percent) — together some 929,000 deaths a year at the time of estimation, split between 446,000 from cirrhosis and 483,000 from liver cancer [1].
The two diseases have opposite shapes, and the contrast is the most useful thing about putting them in one review.
Hepatitis B is preventable by a vaccine and, in most people, controlled rather than cured. The vaccine was the first to be shown to prevent a human cancer. The drugs suppress the virus superbly and eliminate it rarely.
Hepatitis C has no vaccine and is curable. A disease that in 2002 required 48 weeks of injections for a roughly even chance of clearance [2] is now treated with a few months of oral tablets, and cure has become the expected outcome.
What they share is the thing that makes both dangerous: decades of silence. Neither causes symptoms while the damage accumulates, which is why both are usually found either by screening or too late.
Start here: what these viruses do
Both are hepatotropic — they infect hepatocytes — and in both the harm comes not from the virus destroying cells directly but from the immune response to persistently infected liver tissue. Chronic inflammation drives fibrosis; fibrosis, continued long enough, becomes cirrhosis; and cirrhosis is the substrate on which hepatocellular carcinoma arises [3] [4].
Hepatitis B is a DNA virus. Whether infection becomes chronic depends overwhelmingly on the age at which it is acquired: infection in infancy usually becomes chronic, infection in adulthood usually does not. That single fact is why the vaccine's birth dose matters so much, and why the global burden is concentrated in regions where transmission was historically perinatal. Its natural history is conventionally described in phases defined by viral replication, immune activity and the hepatitis B e antigen [5] [6] [7].
Hepatitis B has one feature that shapes everything about its treatment: the virus establishes a stable episomal reservoir in the hepatocyte nucleus — covalently closed circular DNA — which current drugs do not eliminate. Suppressing replication is achievable; clearing the template is not.
Hepatitis C is an RNA virus, transmitted principally through blood: unsafe injections and transfusions historically, injecting drug use predominantly now. Around three quarters of acute infections become chronic. Having no DNA intermediate and no nuclear reservoir, it can in principle be eradicated from the body — and that difference, not any difference in how nasty the two viruses are, is why one is curable and the other is not.
Hepatitis D deserves a mention because it is the most severe form of chronic viral hepatitis and the most neglected. It is a defective satellite virus that cannot replicate without hepatitis B's surface antigen, so it infects only people who already have hepatitis B, and it accelerates their disease [8].
Pillar 1: measurement and diagnosis
Hepatitis B: a panel of markers, each answering a different question
The serology looks intimidating and is actually a small logic puzzle worth learning, because each marker means one thing.
HBsAg — hepatitis B surface antigen — means the virus is present. Its persistence beyond six months defines chronic infection, and its loss is the closest thing to a cure that current therapy achieves.
Anti-HBs — antibody to that surface antigen — means immunity, whether from vaccination or from resolved infection. A vaccinated person has anti-HBs and nothing else.
Anti-HBc — antibody to the core antigen — means exposure to the actual virus at some point. This is what separates vaccination (anti-HBs alone) from past natural infection (anti-HBs plus anti-HBc).
HBV DNA quantifies how much virus is replicating. As the centerpiece shows, this is not merely a treatment-monitoring number: it is the strongest available predictor of what will happen to the liver over the following decades [9].
HBeAg and its antibody mark replicative phase and are used, with HBV DNA and transaminases, to decide who needs treatment [6] [7].
Hepatitis C: two tests, in sequence, and the second is the one that counts
Anti-HCV antibody identifies anyone who has ever been infected. It stays positive after cure, so on its own it cannot distinguish current infection from a resolved one.
HCV RNA answers the question that matters: is the virus present now? A positive antibody with a negative RNA means past infection, spontaneously cleared or treated. This two-step sequence is the entire diagnostic algorithm, and the failure mode is stopping after the first step.
Staging the liver, which is shared with the rest of hepatology
Once infection is established the clinical question becomes how much fibrosis there is, because that is what determines prognosis and surveillance. Fibrosis stage, and not inflammation or steatosis, is what predicts long-term outcomes [10].
FIB-4 is a simple index computed from age, transaminases and platelet count, requiring no extra test [11]. Transient elastography measures liver stiffness by timing a shear wave, non-invasively [12]; it has been compared prospectively against biopsy and other markers in chronic hepatitis C [13], meta-analysed for staging performance [14] [15], and validated specifically for diagnosing cirrhosis [16] [17]. Biopsy remains available for ambiguous cases, but is no longer the routine first move. This is the same staging toolkit used in metabolic liver disease, and the reason the two literatures share instruments.
Once cirrhosis is present, surveillance for liver cancer begins — ultrasonography at intervals, with or without alpha-fetoprotein — because hepatocellular carcinoma is curable when small and not when large [18] [19] [20] [21]. Decompensated cirrhosis has its own management [22].
Centerpiece: a simple simulatable model of how the risk compounds
The reason to treat someone who feels well is that risk in chronic viral hepatitis accumulates over decades and scales with how much virus is present. Both halves of that sentence were measured in a single study.
The REVEAL-HBV cohort followed 3,653 hepatitis B surface antigen-positive adults in Taiwan through 41,779 person-years, recording 164 incident hepatocellular carcinomas over a mean follow-up of 11.4 years. Incidence rose across strata of baseline HBV DNA in a dose-response relationship, from 108 per 100,000 person-years below 300 copies per millilitre to 1,152 per 100,000 person-years at a million copies or more — a more than tenfold gradient — with corresponding cumulative incidences of 1.3 and 14.9 percent [9].
Treating the incidence within a stratum as a constant hazard gives the cumulative risk after t years as 1 − exp(−ht). There are no free parameters; h is measured, one value per stratum.
The model is checked against a number it was never given. Supplied only with the incidence rates, it implies how long follow-up must have been to reach each stratum's reported cumulative incidence: 14.0 years for the high-viraemia group and 12.1 years for the low — both close to the actual 11.4-year mean follow-up. That the high stratum implies the longer duration is informative rather than embarrassing: a constant hazard slightly under-predicts risk where liver disease is actively advancing, because in reality the hazard accelerates as cirrhosis develops.
Run the model forward and the compounding is stark. At 30 years of chronic infection the high-viraemia curve reaches 29 percent and the low-viraemia curve 3 percent — a gap of 26 percentage points, or 260 liver cancers per 1,000 people. At 10 years the gap is only 10 points. The disease is not dangerous because any single year is dangerous; it is dangerous because the years add up.
That gap is the case for treatment, and it is why the model is drawn this way. Antiviral therapy for hepatitis B does exactly one thing well: it drives HBV DNA down. In the terms of this figure, effective suppression moves a patient from the top curve toward the bottom one. The vertical distance between them is an estimate of what that is worth, and it widens with every year of treatment — which is the reason therapy is generally lifelong.
And it is why vaccination dominates everything. A vaccinated person never enters this figure at all. Taiwan's universal hepatitis B vaccination programme, begun in 1984, was followed by a decline in childhood hepatocellular carcinoma incidence from 0.70 per 100,000 children aged 6 to 14 in 1981–1986 to 0.36 in 1990–1994; among children aged 6 to 9 the rate fell from 0.52 for those born in 1974–1984 to 0.13 for those born in 1984–1986 [23]. Longer follow-up confirmed the effect at 20 and 30 years [24] [25]. This was the first demonstration that a vaccine could prevent a human cancer.
Three honest limits. A constant hazard is an approximation, and the check above detects its direction of error. Reading the gap between strata as a treatment effect assumes that suppressing virus confers the risk of the naturally low-DNA stratum, which is an extrapolation from an observational gradient rather than a randomised result — plausible, widely accepted, and not the same thing as proven. And the cohort was Taiwanese adults aged 30 to 65 with genotypes and exposures particular to that setting.
Pillar 2: treatment and prevention
Hepatitis B: prevent it, or suppress it
The vaccine is the single most effective intervention in this review, and the birth dose is its critical component, because it interrupts the perinatal transmission that produces lifelong chronic infection [23] [25].
Antiviral therapy uses nucleos(t)ide analogues — tenofovir and entecavir are the current first-line agents — which inhibit the viral polymerase. They are extraordinarily effective at suppression and unimpressive at cure, and the registration trials show both halves at once. In 715 treatment-naive HBeAg-positive patients, entecavir produced undetectable HBV DNA in 67 percent at 48 weeks against 36 percent for lamivudine, with histological improvement in 72 versus 62 percent and no detected entecavir resistance — but HBeAg seroconversion occurred in only 21 percent, no better than lamivudine's 18 percent [26]. The same pattern held in HBeAg-negative disease [27]. Earlier agents suppressed less durably and selected resistance [28], and lamivudine nonetheless delayed clinical progression in patients with advanced fibrosis [29]. Interferon remains an option for a minority, with a finite course and a chance of durable off-treatment response [30].
The honest summary: these drugs reliably control the virus and reliably do not clear it, because they do not touch the nuclear template. Stopping usually means relapse. Therapy is, for most patients, indefinite.
Hepatitis C: cure it
The old regimen is worth stating because it measures how much changed. In 2002, peginterferon alfa-2a plus ribavirin for 48 weeks — weekly injections, with substantial haematological and psychiatric toxicity — produced a sustained virological response in 56 percent of patients [2]. That was the state of the art, and it was a coin flip with a year of misery attached.
Direct-acting antivirals replaced it entirely. They target three viral proteins directly: the NS3/4A protease, the NS5A protein required for replication and assembly [31], and the NS5B polymerase. Combining agents against two or three of these in a single oral regimen, taken for a couple of months, made sustained virological response the expected outcome rather than a gamble — and the tell is in the literature itself: the cohort studies that now exist are studies of what happens after cure, in patients described without qualification as cured [32] [33] [34]. Regimens have been extended to populations previously considered hard to treat, including people with advanced kidney disease [35] and people who inject drugs [36].
Sustained virological response is a cure, and it matters. In HALT-C, among patients with histologically advanced chronic hepatitis C, the adjusted cumulative rate of death or liver transplantation at 7.5 years was 2.2 percent in those who achieved sustained response against 21.3 percent in non-responders, with liver-related morbidity and mortality of 2.7 versus 27.2 percent, and a hazard ratio for hepatocellular carcinoma of 0.19 [37].
But cure does not abolish liver cancer risk, and this is the most misunderstood point in the field. The HALT-C authors state it plainly: patients who clear the virus "remain at risk for HCC" [37]. Cirrhosis already established does not reverse quickly, and the cancer arises from the scarred liver rather than from the virus directly. A brief controversy over whether direct-acting antivirals might increase early cancer occurrence [38] was addressed by larger analyses concluding that eradication reduces risk [33] [34] [39] [32]. Cured patients with cirrhosis need lifelong surveillance. Cure changes the trajectory; it does not erase the history.
Pillar 3: what is unresolved
Functional cure for hepatitis B. The goal is sustained loss of surface antigen off treatment, which current nucleos(t)ide analogues achieve rarely [26]. Doing better requires attacking the nuclear reservoir or restoring immune control rather than merely blocking the polymerase — the central problem in the field, and unsolved.
Elimination of hepatitis C. With a curative oral therapy and no vaccine, the constraint is entirely diagnostic and operational: most infected people do not know they are infected, and the two-step antibody-then-RNA algorithm loses people between steps. Simplified test-and-treat pathways in the populations where transmission actually occurs [36] are what elimination depends on, not new drugs.
A hepatitis C vaccine. There is none, and the virus's genetic diversity and capacity for escape make it hard. As long as cure is available but prevention is not, reinfection after cure remains possible in people with ongoing exposure.
Hepatitis D. The most severe chronic viral hepatitis has had the least to offer. Interferon was for decades the only option and a poor one [40]; entry inhibition by blocking the bile-acid transporter the virus uses to enter hepatocytes produced the first genuinely new results [41], and formal guidance now exists [8].
Vaccine coverage. The hepatitis B vaccine works, has worked for forty years, and prevents a cancer [23] [24] [25]. The remaining burden is largely a birth-dose coverage problem in the regions where perinatal transmission still occurs, which is an implementation failure rather than a scientific one.
Dig deeper in lmmol
Viral hepatitis and fatty liver disease converge on the same endpoint by different routes, and share the same instruments for measuring it — FIB-4, transient elastography, and the finding that fibrosis stage rather than inflammation predicts outcome [10] [11] [12]. Increasingly they occur in the same patients, and metabolic and viral injury compound. HIV shares transmission routes with hepatitis B and C, coinfection is common and accelerates liver disease, and tenofovir treats both HIV and hepatitis B — which is why HIV programmes are also hepatitis B programmes. Hemochromatosis reaches cirrhosis and liver cancer by a third route entirely, iron rather than virus or fat, and its raised ferritin is a recurring differential here. The screening logic that governs liver cancer surveillance in cirrhosis has instructive parallels in colorectal cancer and breast cancer, where the same question — who to watch, how often, with what test — has been worked out at greater scale. For another infection where a vaccine exists and coverage is the binding constraint, see measles. The full collection is at health.