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Qu et al. Etiological prevention of liver cancer

are uniformly resistant to chronic HBV infection when infection among vaccinated young adults [87,88] , it might
they grow up and engage in risky behaviors that might be appropriate to receive the adolescent boosters,
increase HBV exposure. especially for the high-risk individuals [33,56,80,82,88] .

Studies were done to examine the different responses Experience and recommendation to reduce
to booster doses conducted in different areas, to liver cancer risk beginning at birth by
determine if this might be due to enrolling populations preventing chronic HBV infection
with different or unknown maternal HBsAg status. To control chronic HBV infection, plasma-derived
Recently, by enrolling the participants of the vaccination HBV vaccine, the first generation vaccine, had been
group in the QHBIS, Wang et al. [54] addressed the administered to millions of infants. In addition, due to
question of adolescent booster effect against HBV various reasons, the HBIG was not administered to
infection in individuals born to mothers with different high-risk infants who were born to HBsAg-positive
HBsAg-carrying status [54] . In this study, a total of 9,793 mothers in many low- and middle-income countries and
vaccinated individuals, who were HBsAg(-) at childhood areas [23] . The plasma-derived HBV vaccine has now
(10-11 years of age), re-donated their blood samples been totally replaced by recombinant HBV vaccines,
for HBV serological surveys in mature adulthood (23- and most of the high-risk infants were immunized
28 years of age). Among them, a total of 7,414 children together with HBIG administration.
received one dose (10 μg) of recombinant HBV vaccine
booster and 2,379 did not receive the adolescent As the population who was vaccinated with plasma-
booster. Although the booster was not randomized, the derived HBV vaccine stepped into their third decades,
distributions between the participants who received the we can get further insights from them by monitoring their
booster and those who did not receive the booster were HBV serological markers, and disease development.
similar in age, gender, maternal HBsAg status, maternal The studies based on QHBIS provided some
childbearing age, and family income per capita. Their information on HBV vaccination strategies in controlling
results showed that HBV breakthrough infection occurred chronic HBV infection, liver cancer, and chronic liver
in the vaccinated individuals, who had been protected at failure. Our accumulated clinical data on using antiviral
childhood by a neonatal vaccination series. Some of the therapies in HBV-infected Chinese pregnant women
infection developed chronicity in adulthood, especially with higher viremia have shown efficacy in blocking
among the individuals who were born to HBsAg-positive MTCT transmission of HBV. All these experiences will
mothers and lost anti-HBs or anti-HBs < 10 mIU/mL in be helpful for better controlling PLC, especially HCC, by
the childhood. Hence, some of the adolescents born to eradicating HBV beginning at birth.
HBsAg-positive mothers might be susceptible to chronic
HBV infection if serum anti-HBs is < 10 mIU/mL [95,96] . The experiences and recommendations are as follows
[Table 1]: (1) in endemic regions, HBV vaccination
Further analysis showed that one dose of adolescent in neonates is crucial against chronic HBV infection.
booster provided protection (against chronic HBV Although catch-up vaccination given after age 10
infection in adulthood) to these high-risk individuals who was useful, the protection efficacy was substantially
were born to HBsAg-positive mothers and had lost anti- weaker compared to neonatal vaccination; (2) children/
HBs or had anti-HBs < 10 mIU/mL. Nevertheless, no adolescents born to mothers with different HBsAg-
booster effect was observed in those who were born to status had distinct immunity against chronic HBV
HBsAg-negative mothers, regardless of their anti-HBs infection, even after initial protection offered by HBV
status at 10-11 years of age when they completed the vaccination. The adolescents/young adults seem to
neonatal three-dose HBV vaccine series. The difference be susceptible to chronic HBV infection when they
in immunity in the HBV-exposed neonates was proven were born to HBsAg-positive mothers when they have
to be very different from the healthy ones [89] . When they lost anti-HBs or when their anti-HBs is < 10 mIU/mL.
grow up, their immunity and the immunological memory It is recommended to have at least one booster dose
in the prenatal HBV-exposed individuals seem to be also given during adolescence to those who were born to
different in their response against chronic HBV infection. HBsAg-positive mothers and had lost anti-HBs or when
The presence of immunological memory and effect of their anti-HBs is < 10 mIU/mL, to ensure the immunity
adolescent booster should be re-visited [95,96] . A recent against chronic HBV infection; (3) to prevent MTCT
study reported that the HBsAg prevalence was 6.35- transmission of HBV, screening for HBsAg in the first
6.47% in men aged 25-39 years living in the rural areas trimester of pregnancy is strongly recommended; (4)
of China [97] , indicating the high risk of HBV infection For pregnant women with serum HBV DNA levels >
upon sexual, parenteral, or horizontal (household) 200,000 IU/mL, antiviral treatment is recommended.
HBV exposure. Following the documentation of HBV Therapy with tenofovir or telbivudine should start at
236 Hepatoma Research ¦ Volume 3 ¦ October 25, 2017