Occult hepatitis B infection (OBI): a debate on HBV vaccination paradigm

Occult hepatitis B infection (OBI): a debate on HBV vaccination paradigm
Sara Delghandi,¹ Sahar Shahtahmasbi,² Zahra Meshkat,³ Hamed Gouklani,⁴ Aida Gholoobi,^5,*
1. Department of Immunology, Faculty of medicine, Mashhad University of Medical Sciences, Mashhad, Iran
2. Department of Laboratory Sciences, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
3. Antimicrobial Resistance Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
4. Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences,Bandar Abbas, Iran
5. Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
Introduction: Chronic HBV infection endangers the lives of 257 million carriers worldwide as it may lead to severe conditions such as liver cirrhosis or hepatocellular carcinoma. The current yeast-derived vaccines are the most effective strategy to prevent hepatitis B diseases. However, along with the growth of research around occult HBV infection (OBI) in immunized individuals and the residual risk of mother-to-child-transmission in 10-30% of infants born to HBsAg positive mothers, there is increasing concern that HBV vaccines cannot guarantee complete protection. The aim of this study is to provide better insight into the impacts of the general HBV vaccination program on OBI and to address the major drawbacks of current vaccines.
Methods: We searched PubMed, Scopus, and Web of Science databases to identify studies on OBI among vaccinated populations. A total of 73 eligible studies published between 2004 and 2018 were identified.
Results: We found several studies reporting the emergence of OBI in fully vaccinated individuals of both the general population and high-risk groups such as newborns of HBsAg positive mothers. Low-level anti-HBs and high maternal viral loads in MTCT cases as well as vaccine escape mutants and heterologous HBV genotypes are the factors contributing to vaccine failures.
Conclusion: Further research is required in order to clarify the precise impact of active immunization on the emergence of OBI in the vaccinated population. However, what is certain is that with the development of more potent HBV vaccines, the eradication of HBV would be more imaginable.
Keywords: General population; Mother-to-child-transmission; Hepatitis B vaccine; Chronic Hepatitis B