About 300m people worldwide are living with hepatitis B, yet the majority of cases remain undiagnosed or untreated – The Guardian reports that a study has found roughly 90% of people infected by the virus, which is incurable but manageable, are unaware they have it.
A vaccine that provides lifelong immunity is available, but only half of all babies globally receive it. Moreover, fewer than 1% of all hepatitis B-infected mothers – who are the primary source of infection and are at high risk of passing the virus to their children – are receiving appropriate treatment.
The report says the study’s authors warn that global efforts aimed at eradicating the hepatitis B virus (HBV) by 2030 are unlikely to be met unless countries rapidly improve access to screening and treatment. The World Health Organisation (WHO) recommends that all newborns receive their first dose of a highly effective vaccine, which has been available since 1981, within 24 hours of birth.
“Most mother-to-child transmission occurs within days of birth, so the birth dose is vital,” said primary investigator Dr Homie Razavi, of the Centre for Disease Analysis Foundation, a public health research firm based in Colorado. “We have all the tools necessary to eliminate HBV. Our estimates highlight an enormous opportunity for effective screening, diagnosis, and treatment to substantially reduce the numbers of new infections in all countries by 2030,” he said. “But we must accelerate efforts across the board. We hope this work will be the catalyst to support national strategies to eliminate the virus by 2030, which 194 countries have pledged to do.”
The report says the highly contagious virus is most prevalent in east Asia and sub-Saharan Africa, according to the report. China, India, Indonesia, Nigeria and the Philippines account for more than 57% of all infections. In Central African Republic, 12.1% of the population is estimated to be living with the virus, while in Taiwan the figure is 9.4%. The UK, in comparison, accounts for just 0.7% of infections.
Although a test to detect the virus has been available since the 1970s, only one in 10 of those infected globally – roughly 29m people – had been diagnosed by 2016, according to the authors. Rates of diagnosis, as well as treatment, are far lower than they should be, even in higher income countries. Two-thirds of those infected with HBV in the US, and four in five in the UK, are unaware of their infection.
The report says researchers estimate that only about 5% of those suitable for treatment are receiving it. However, of the 120 modelled countries, 22 were estimated to have already reached the 2020 target of diagnosing one-third of the infected HBV population. A huge worldwide effort will be needed to meet the 2030 target of 90% diagnosis – with 80% of those eligible treated – said the authors, who pointed out that screening programmes would have to be widened beyond pregnant women alone. In Pakistan, the report points out, the HBV birth vaccine and protective antibodies known as HBIG, are only available on the private market.
Geoffrey Dusheiko, emeritus professor of medicine at the University College London Institute for Liver and Digestive Health and King’s College Hospital, said governments need to start addressing HBV in a similar vein to how HIV is currently screened and managed.
“Chronic hepatitis B is a leading cause of liver cancer but it causes silent liver disease – it can remain silent and hence undiagnosed for several decades, until individuals present for the first time in young adulthood or mid-life with decompensated cirrhosis, liver failure, or hepatocellular carcinoma,” said Dusheiko.
“To reach those (2030) targets, we are going to have to diagnose a vast number of individuals – some 250m people – perhaps approximately 100m of whom require treatment.
“Some of the required pressure for wider testing will have to come from a populace that is made aware (of the risks but also potential treatment of chronic hepatitis B), and to raise awareness to the same level as HIV infection. That may spur individuals to get tested, and in turn will spur governments in high prevalence regions, several of which are low-income countries, to subsidise testing and linkage to treatment.
“A test for hepatitis B only costs $1 or $2 but you need the information, infrastructure and will.”
Summary
Background: The 69th World Health Assembly approved the Global Health Sector Strategy to eliminate viral hepatitis by 2030. Although no virological cure exists for hepatitis B virus (HBV) infection, existing therapies to control viral replication and prophylaxis to minimise mother-to-child transmission make elimination of HBV feasible. We aimed to estimate the national, regional, and global prevalence of HBsAg in the general population and in the population aged 5 years in 2016, as well as coverage of prophylaxis, diagnosis, and treatment.
Methods: In this modelling study, we used a Delphi process that included a literature review in PubMed and Embase, followed by interviews with experts, to quantify the historical epidemiology of HBV infection. We then used a dynamic HBV transmission and progression model to estimate the country-level and regional-level prevalence of HBsAg in 2016 and the effect of prophylaxis and treatment on disease burden.
Findings: We developed models for 120 countries, 78 of which were populated with data approved by experts. Using these models, we estimated that the global prevalence of HBsAg in 2016 was 3·9% (95% uncertainty interval [UI] 3·4–4·6), corresponding to 291 992 000 (251 513 000–341 114 000) infections. Of these infections, around 29 million (10%) were diagnosed, and only 4·8 million (5%) of 94 million individuals eligible for treatment actually received antiviral therapy. Around 1·8 (1·6–2·2) million infections were in children aged 5 years, with a prevalence of 1·4% (1·2–1·6). We estimated that 87% of infants had received the three-dose HBV vaccination in the first year of life, 46% had received timely birth-dose vaccination, and 13% had received hepatitis B immunoglobulin along with the full vaccination regimen. Less than 1% of mothers with a high viral load had received antiviral therapy to reduce mother-to-child transmission.
Interpretation: Our estimate of HBV prevalence in 2016 differs from previous studies, potentially because we took into account the effect of infant prophylaxis and early childhood vaccination, as well as changing prevalence over time. Although some regions are well on their way to meeting prophylaxis and prevalence targets, all regions must substantially scale-up access to diagnosis and treatment to meet the global targets.
Authors
The Polaris Observatory Collaborators
[link url="https://www.theguardian.com/global-development/2018/mar/27/scientists-warn-90-of-hepatitis-b-sufferers-remain-unaware-of-silent-killer"]The Guardian report[/link]
[link url="http://www.thelancet.com/journals/langas/article/PIIS2468-1253(18)30056-6/fulltext"]The Lancet Gastroenterology & Hepatology article summary[/link]