Absence of chronicity in infants born to immunized mothers with occult HBV infection in Taiwan

BACKGROUND & AIMS

In the Taiwanese population born in the universal vaccination era, HBsAg carrier rates have fallen below 2%, while approximately 5% develop occult hepatitis B infection (OBI). However, the potential for transmission from mothers with OBI to their infants has not been well studied. We aimed to investigate whether mothers with OBI could transmit HBV to their babies.

METHODS

A total of 253 pregnant women who were born after July 1986 and had been fully vaccinated against HBV during infancy were recruited from a tertiary hospital in Northern Taiwan. HBV serology and DNA levels were determined. Babies born to mothers with OBI were followed-up until 1 year of age. The surface genes were sequenced.

RESULTS

HBV infection was documented in 18 vaccinated mothers, 2 of whom were HBsAg-reactive (0.79 %). Seventeen were positive for HBV DNA, among whom 16 (6.32%) presented with OBI with a median DNA level of 145 IU/ml (interquartile range: 37.8-657.3 IU/ml). Eleven babies born to 10 mothers with OBI were recruited. Three babies were HBsAg-reactive, and 2 were positive for HBV DNA (17.0 and 212.0 IU/ml). Seven mothers with OBI carried multiple surface gene variants. Two transiently infected babies harbored variants originating from their mother's HBV quasi-species. All infants received complete hepatitis B vaccines. At 12 months of age, none of the babies were positive for HBsAg or HBV DNA.

CONCLUSIONS

It was possible for mothers with OBI to transmit HBV to their babies, who consequently harbored surface gene variants originating from their mothers' minor variants. Viremia was cleared 1 year after completing the hepatitis B vaccination series.

LAY SUMMARY

Since initiating the hepatitis B vaccination program in Taiwan, the rate of young individuals (i.e. born after 1986) carrying the HBV surface antigen has fallen below 2%, although around 5% of vaccinated individuals develop occult HBV infections. Herein, we show that pregnant mothers with occult HBV infections can transmit HBV to their offspring. However, no infant had sustained infection at 1 year of age having completed a full HBV vaccination series.

Prevalence of occult HBV infection in Western countries

Due to a lack of standardized tests, it is difficult to obtain prevalence data and define the real impact of occult HBV infection (OBI) in Western countries. The present review article addresses the prevalence of OBI, defined as presence of hepatitis B virus (HBV) DNA in liver tissue or plasma in HBsAg-negative subjects, in Western countries. This varies in different studies according to the different methodologies used (based on serology vs virology), to the sample analyzed for the diagnosis (liver tissue vs plasma), to the different populations studied, to the different geographical variations in the HBV spread, to the host characteristics (age, gender, risk factors for acquiring HBV infection) and to the presence of other parenteral infections (hepatitis C virus and/or human immunodeficiency virus [HIV] infections). Considering the different liver diseases analyzed, that is in patients with cryptogenic cirrhosis or advanced liver fibrosis, the prevalence of OBI ranges 4% to 38%. Considering the different populations studied, in the case of parenteral blood exposure it is about 45%, in patients with chronic hepatitis C it is estimated at about 52%, in HIV-infected patients it ranges from 0% to 45%, in blood donors from 0% to 22.7% and in hemodialysis patients it ranges from 0% to 54%. In conclusion, OBI is a virological entity to be considered when performing the patient's evaluation for immunosuppressive diseases, liver pathologies, or for blood transfusions. Knowing the prevalence and clinical impact of OBI will allow better patient management.

An estimation of the prevalence of occult HBV infection in Western Europe and in Northern America: A meta-analysis

Data on the prevalence of occult HBV infection (OBI) in Western Europe and in Northern America are few; hence, we conducted a systematic review and meta-analysis. All studies included had to fulfil the following inclusion criteria: (a) they investigated the prevalence of OBI (HBV DNA in liver tissue in HBsAg-negative subjects), (b) were carried out in Western Europe and in Northern America; (c) were available as a full-text manuscript, (d) written in English and (e) published up to December 2018. The exclusion criteria were as follows: (a) meta-analyses, letters, reviews, meeting abstracts or editorial comments; (b) studies investigating HBsAg-positive patients; (c) those investigating OBI outside Western Europe and in Northern America; and (d) to avoid small sample bias in the random-effects model, those enrolling less than five subjects. Thirty-four studies met the inclusion criteria, allowing a meta-analysis on 2729 patients. The overall prevalence of OBI was 34% (95% CI = 26%-42%), 28% (CI 95%: 12%-48%) in 329 subjects without chronic liver disease and 35% (95% CI 26%-44%) in 2400 patients with chronic liver disease. The prevalence of OBI was 51% (95% CI 40%-62%) in the 823 anti-HBc-positive subjects and 19% (95% CI 10%-30%) in the 1,041 anti-HBc-negative subjects. Evaluating the data from 17 studies comparing anti-HBc-positive and negative subjects, the prevalence of OBI was higher in the 641 anti-HBc-positive subjects than in the 1041 anti-HBc-negative (prevalence ratio = 2.29; 95% CI = 1.61-3.26, P < .001). This meta-analysis showed that in HBsAg-negative subjects the prevalence of OBI was high and was associated with anti-HBc positivity.

Eighteen-month lamivudine prophylaxis on preventing occult hepatitis B virus infection reactivation in patients with haematological malignancies receiving immunosuppression therapy

This study evaluated the long-term efficacy and safety of an 18-month lamivudine prophylaxis in 68 HBsAg-negative/anti-HBc-positive patients with oncohaematological disease. All 68 consecutive HBsAg-negative/anti-HBc-positive patients with an oncohaematological disease and naïve for chemotherapy observed from April 2008 to December 2012 at 2 Hematology Units in Naples were treated with lamivudine for 18 months after stopping chemotherapy and monitored for HBsAg at months 1 and 3 during chemotherapy and then every 3 months after its discontinuation. During follow-up, 13 (19.1%) of the 68 patients died of complications related to their oncohaematological disease, and 3 (4%) showed a virological HBV reactivation (retroconversion to HBsAg positivity) 1-7 months after the discontinuation of lamivudine prophylaxis (2 treated for chronic lymphocytic leukaemia and one for Waldenstrom's disease); of these, 2 showed a biochemical reactivation. Comparing the demographic and clinical characteristics of the 3 patients with a virological HBV reactivation to the 65 without, the former were older (median age and range: 67 years [75-78] vs. 61 [24-88]; P = .05) and were less frequently treated for B-cell non-Hodgkin lymphoma (B-NHL) (0 vs. 70.7%, P = .03). In conclusion, a 18 months of lamivudine prophylaxis was effective in preventing HBV reactivation in HBsAg-negative/anti-HBc-positive patients treated for B-NHL. However, in patients with chronic and severe immunodepression, such as those with chronic lymphocytic leukaemia and Waldenstrom's disease, prophylaxis should be continued for an indefinite period.