The primary aim of the study is to accomplish two major tasks: the first is to determine the frequency of intra-familial transmission of HBV; the second is trying to explore the potential risk factors of such a transmission .As a secondary aim, immunologic status of the household contacts vaccinated for hepatitis B will be evaluated to assess the efficacy of hepatitis B vaccination and its role in prevention of intra-familial transmission of HBV

Hepatitis B virus (HBV) infection is a global health issue; it is estimated that 257 million persons have chronic HBV (Asgeir et al., 2021). The major routes of HBV transmission include blood, sexual contact, vertical (from infected mothers to her children) and horizontal (between the spouses or children) transmission (Şükran et al., (2018). The household transmission of HBV is also a major health issue; it represents a challenge to the health system. Higher rates of HBV infection were reported among the household contacts of chronic HBV carriers; the prevalence of HBV infection among the family members of patients with chronic HBV can reach to 57%. Factors affecting the risk of transmission include socio-demographic status, family role (infected mothers increase the risk of transmission) and viral markers of the index case (Masomeh et al., 2016).The diagnosis of HBV infection is generally based on serological (hepatitis B surface antigen) and molecular assays (hepatitis B virus deoxyribonucleic acid) (Chen et al., 2017).Although the three-dose vaccination for hepatitis B provides more than 90% seroprotection rates (Van Den Ende C, et al, 2017); approximately 10% of vaccinated persons may be at risk of getting infected.

Available data about the current status of intra-familial transmission of HBV among our community members are lacking; we need to determine the magnitude of such a major public health problem

Inclusion Criteria:

• : The household contacts of patients with chronic HBV infection will be included in the study.

Exclusion Criteria:

• Those with prior diagnosis of HBV infection following the date of the primary case infection.

We will provide clinical evaluation, laboratory investigations, and abdominal ultrasonography for every participant of the study. Clinical evaluation will include a detailed questionnaire concerning the potential risk factors of intra-familial transmission of HBV; it will include the kind of family relationship, demographic data, history of hepatitis B vaccination, and the potential routes of HBV transmission. The battery of laboratory work will include hepatitis B surface antigen (for diagnosis of infection), and titer of antibody to hepatitis B surface (for assessment of the immunologic status among non-infected subjects). In addition, liver chemistry panel will be performed for infected patients to help in the assessment of liver disease severity.