Ninety per cent of people with
chronic hepatitis B virus (HBV) are undiagnosed, according to research
published in The Lancet Gastroenterology &
Hepatology. The study also showed that just 5% of eligible patients are
receiving HBV therapy. These proportions are well below those needed to achieve
the World Health Organization (WHO) target of eliminating HBV as a health threat by 2030.
“Successive governments in
high-prevalence regions have accepted the doctrine of vaccination, but have
overlooked the larger picture of screening, diagnosis, and treatment to prevent
progression,” comment the authors of an editorial accompanying the study. “The
incidence of new chronic HBV infections will increase in unvaccinated adults
unless large increases in screening and linkage to care are implemented.”
In 2016, WHO set the target of
eliminating chronic HBV as a public health threat by 2030. Although there is
no cure for HBV, there is a highly effective vaccine and the infection can be
controlled by treatment with antiviral drugs.
Elimination of HBV by 2030 will
require:
- 90% coverage of three-dose infant vaccination by
2020
-
Timely birth-dose vaccination in 50% of infants
by 2020, reaching 90% by 2030
-
Chronic HBV prevalence in children of 1% by 2020
and 0.1% by 2030
-
Diagnosis of 90% of people infected with HBV
-
Antiviral treatment of 80% of diagnosed people
eligible for therapy.
To enable monitoring of progress
towards these targets, a team of investigators estimated national, regional and
global prevalence of HBV, as well as rates of diagnosis, vaccination and
treatment. Data were obtained from published studies, government reports and
interviews with national experts.
On the basis of these data, the
investigators calculated that 364 million individuals – 5% of the world
population – had chronic HBV infection. But after taking into account
epidemiology, demographic changes, vaccination coverage, treatment and
diagnosis, the researchers revised their prevalence estimate down to 4% of the
world population.
Prevalence was highest in East Asia
and sub-Saharan Africa, reaching 12% in the Central African Republic, compared
to less than 1% in the UK. Just 21 countries accounted for 80% of all cases of
chronic HBV in 2016. Moreover, 57% of these infections were in five countries:
China, India, Nigeria, Indonesia and the Philippines.
Global diagnosis rates were poor.
Even though an accurate test has been available since the 1970s, only 10% of people with the infection had been diagnosed in 2016. Diagnosis was not just a problem
for poor countries: two-thirds of those
with chronic HBV in the US and 80% in the UK were unaware of their infection
status.
Only a small fraction of eligible
people – 5% – were receiving anti-HBV
drugs. Treatment coverage was even poor in Western Europe: just 3% in Belgium,
5% in Ireland, Norway and Portugal and 25% in the UK.
Globally, less that 1% of expectant
mothers with a high HBV viral load received antiviral prophylaxis to prevent
mother-to-child transmission.
In 2016, an estimated 1.4% (1.8
million) five year olds had chronic HBV. Globally, 87% of
infants received the three doses of the vaccine needed to prevent infection.
Encouragingly, 94 of the 120 countries included in the study had already met
the interim 2020 target of 1% prevalence among five year olds and 46 had
achieved the 2030 target of 0.1% prevalence.
Despite these positive data, only
48% of babies were receiving their first vaccination dose within the crucial
first 24 hours after birth, and just 10% of infants were receiving protective
antibodies – hepatitis B immunoglobin (HBIG) – along with the full vaccination
strategy. It was only in 2017 that the UK and Norway introduced routine HBV
vaccination for newborns.
Most of the countries with a high
burden of infant HBV have yet to fully scale up infant vaccination and to
provide HBIG.
“We have all the tools necessary to
eliminate hepatitis B in children. In spite of this, 1.8 million children aged
5 years were infected with HBV in 2016, with a very similar number of new infections
occurring annually,” conclude the authors. “This analysis provides a marker on
the road to elimination by quantifying the use of prophylaxis and treatment at
the national, regional, and global levels. This work can support national
strategies to eliminate HBV and decrease the number of new infections by 90% by
2030.”