While universal infant hepatitis B virus (HBV) vaccination has already led to major advances in reducing new infections in some settings, further expansion of prevention and treatment are needed to significantly reduce HBV transmission and liver disease mortality, according to an analysis presented at the European Association for the Study of the Liver (EASL) 50th International Liver Congress this week in Vienna, Austria.
Many countries, including the UK, recommend that all infants be vaccinated against HBV starting soon after birth, but vaccine coverage remains incomplete in many areas and hepatitis B still accounts for up to 1 million deaths annually worldwide. Over years or decades, chronic HBV infection can lead to advanced liver disease including cirrhosis and hepatocellular carcinoma.
Shevanthi Nayagam from Imperial College London and colleagues developed a mathematical model to assess the potential impact of scaling up interventions against hepatitis B and to determine realistic targets for elimination of HBV transmission and related mortality.
The model incorporated data on hepatitis B epidemiology, HBV vaccination coverage, treatment and natural history of hepatitis B. This model was used to generate predictions about incidence of new chronic HBV infections, hepatitis B prevalence and HBV-related mortality, looking first at current vaccination and treatment levels and then at scenarios involving scaled-up prevention and treatment interventions.
According to the model, the current level of infant HBV vaccination is already driving a decrease in new infections. If maintained at this level, an estimated 1.2 million new infections will be averted by 2030. However, this would also result in a larger proportion of HBV infections being due to mother-to-child transmission.
Without further intervention, the number of people living with hepatitis B will remain at current high levels for the next 40-50 years and there will be 20 million HBV-related deaths by 2030, the model predicted.
However, the expanded intervention model predicted that incidence of new cases of chronic HBV infection could be reduced by 90% and mortality could fall by 65% by 2030 if the following interventions are implemented:
- Infant vaccination scaled up to >95%
- 80% receive the birth dose of the vaccine and hepatitis B immune globulin (HBIG) and antivirals to interrupt mother-to-child transmission
- A 90/90/90 strategy for people already infected: 90% screened for HBV, 90% of those eligible being treated, and 90% of those treated achieving durable viral suppression from the year 2020 onward.
This translates to an estimated 13 million deaths averted worldwide, including 6 million due to cancer. The projected global cost for expanded prevention and treatment would peak at US$7.5 billion (£5 billion) annually, but then decline rapidly after 2030.
The researchers noted that these predictions could be accelerated if a finite cure for hepatitis B is developed. Current treatment involves antivirals including tenofovir (Viread) or entecavir (Baraclude), sometimes used with pegylated interferon, but most people are not cured and require long-term therapy.
"[M]aximising prevention interventions (particularly those aimed at preventing infections early in life) and expanding treatment could significantly reduce transmission of infection and mortality, that would move toward elimination of hepatitis B as a public health concern," the researchers concluded. "Although the costs are significant, they peak at lower values and decline more rapidly than those projected for other infectious diseases with similar burden."
Nayagam S et al. What is required for control and elimination of hepatitis B globally? EASL 50th International Liver Congress, Vienna, abstract LP43, 2015.