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Prevalence of occult hepatitis B infection in a highly endemic area for chronic hepatitis B: a study of a large blood donor population
  1. Man-Fung Yuen1,
  2. Cheuk-Kwong Lee2,
  3. Danny Ka-Ho Wong1,
  4. James Fung1,
  5. Ivan Hung1,
  6. Axel Hsu1,
  7. David Yiu-Kuen But1,
  8. Ting-Kin Cheung1,
  9. Pierre Chan1,
  10. John Chi-Hang Yuen1,
  11. Frederic Khe-Cheong Fung1,
  12. Wai-Kay Seto1,
  13. Che-Kit Lin2,
  14. Ching-Lung Lai1
  1. 1Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong
  2. 2Hong Kong Red Cross Blood Transfusion Service, Hospital Authority, Hong Kong
  1. Correspondence to Professor Ching-Lung Lai, Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Pokfulam Road, Hong Kong; hrmelcl{at}


Background and aims The aim of the present study was to determine the population prevalence of occult hepatitis B (OHB) infection and its clinical profile in a highly endemic area of chronic hepatitis B virus disease.

Methods OHB was first identified by individual sample testing for hepatitis B surface antigen (HBsAg) followed by nucleic acid testing (NAT) and vice versa for 3044 (cohort 1, stored sera from donation within 1 year) and 9990 (cohort 2, prospective study) blood donors, respectively. OHB was confirmed meticulously by ≥2 out of 3 tests with detectable hepatitis B virus (HBV) DNA using a sensitive standardised assay. Detailed serology and viral load in the serum and liver were studied.

Results The prevalence of OHB was 0.13% (4/3044) and 0.11% (11/9967) for cohort 1 and 2, respectively. In cohort 2, 10 out of 11 OHB samples were positive for anti-HBc (hepatitis B core antigen) antibody (all were immunoglobulin G). Seven had detectable anti-HBs. The serum HBV DNA levels were extremely low (highest 14.1 IU/ml). Of the six donors who underwent liver biopsies, all had normal liver biochemistry, extremely low liver HBV DNA (highest 6.21 copies/cell) and nearly normal liver histology. For those with viral sequence generation, none had the common HBsAg mutant G145R.

Conclusions The prevalence of OHB in a highly endemic area of chronic HBV was very low, thus implying a low impact on transfusion services. To implement universal screening, the high cost of NAT should be taken into account. OHB blood donors had very low HBV replication, and normal liver biochemistry and histology, conferring a favourable prognosis.

  • Occult hepatitis B
  • prevalence
  • nucleic acid test
  • chronic hepatitis B
  • hepatitis B

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  • Competing interests None.

  • Ethics approval This study was conducted with the approval of the Institutional Review Board of the University of Hong Kong/Hospital Authority Hong Kong.

  • Provenance and peer review Not commissioned; externally peer reviewed.