Epidemiology

The 6 recognised genotypes with numerous subtypes are distributed geographically. Type 4 has a high subtype diversity in Africa, and type 3 in South east Asia. There is very little subtype diversity in Europe and North America suggesting that the virus has only been recently introduced to these areas.

• genotype 1 is the most common in the UK, accounting for about 40-50% of cases. Genotypes 2 and 3 contribute another 40-50%; and genotypes 4, 5 and 6 constitute the remainder, about 5% (1)

In 2015 around 182,400 people (95% credible interval 162,300-203,500) in the UK were living with chronic HCV infection

• prevalence is estimated to have fallen in recent years, and was predicted to have declined to around 143,000 in 2018 (95% CI: 122,400, 164,500). Of these 143,000 chronic infections, two-thirds (95,600; 95% CI 78,300, 113,800) are thought to be undiagnosed

Injecting drug use continues to be the most important risk factor for HCV infection in the UK, with data from UK surveys of people who inject drugs (PWID) suggesting that in 2018, just over half of PWID (54% in England, Wales and Northern Ireland; 57% in Scotland in 2017-18) tested positive for HCV antibody, and just over one quarter had evidence of current infection (27% in the England, Wales and Northern Ireland; 31% in Scotland)

Mortality data suggest a fall in death registrations from HCV-related end-stage liver disease (ESLD) and hepatocellular carcinoma (HCC) of 13% between 2015 and 2017

Reference:

• (1) NICE (August 2006). Guidance on use of peginterferon alfa and ribavirin for the treatment of mild chronic hepatitis C
• (2) Royal College of General Practitioners (RCGP) 2007. Guidance for the prevention, testing, treatment and management of hepatitis C in primary care
• (3) PHE. Hepatitis C in the UK 2019 Working to eliminate hepatitis C as a major public health threat