A Study on the Safety, Efficacy and Immune Response Following Sequential Treatment With an Anti-sense Oligonucleotide Against Chronic Hepatitis B (CHB) and Chronic Hepatitis B Targeted Immunotherapy (CHB-TI) in CHB Patients Receiving Nucleos(t)Ide Analogue (NA) Therapy

Inclusion criteria: * Participants, who, in the opinion of the investigator, can and will comply with the requirements of the protocol. * Written or witnessed/thumb printed informed consent obtained from the participant prior to performance of any study-specific procedure. * A male or female between, and including, 18 and 65 years of age at the time of signing of the informed consent (except for South Korea, where a male or female between, and including, 19 and 65 years of age at the time of signing of the informed consent can participate in the study). * Participants who are Hepatitis B envelop antigen (HBeAg) positive or negative. * Participants who have documented chronic HBV infection \>=6 months prior to screening and currently stable on NA therapy defined as no changes to their nucleos(t)ide regimen from at least 6 months prior to screening and with no planned changes to the stable regimen over the duration of the study. * CHB patient, under and adherent to treatment with a NA with high barrier to resistance (e.g. entecavir, tenofovir disoproxil fumarate and tenofovir alafenamide). * Participants with ALT \<=2x upper limit of normal (ULN) (i.e., no ALT \>2x ULN) documented in approximately the last 6 months. * Participants with plasma or serum HBsAg concentration \>100 IU/mL. * Participants must be adequately suppressed, defined as plasma or serum HBV DNA \<90 IU/mL. * A male participant is eligible if he agrees to the following during the intervention period and for at least 90 days after the last dose of study intervention: * Refrain from donating sperm * AND be abstinent from heterosexual intercourse as their preferred and usual lifestyle (abstinent on a long-term and persistent basis) and agree to remain abstinent OR Must agree to use contraception/barrier as detailed below. * Agree to use a male condom \[and should also be advised of the benefit for a female partner to use a highly effective method of contraception as a condom may break or leak\] when having sexual intercourse with a woman of childbearing potential (WOCBP) who is not currently pregnant. * A female participant is eligible: * If she is not pregnant or breastfeeding * AND at least one of the following conditions applies: * Is not a WOCBP * Is a WOCBP and using a contraceptive method that is highly effective (with a failure rate of \<1% per year), preferably with low user dependency during the intervention period and for at least 90 days after the last dose of study treatment. * A WOCBP must have a negative highly sensitive pregnancy test (urine or serum as required by local regulations) within 24 hours before the first dose of study intervention. Exclusion criteria: Medical conditions * Clinically significant abnormalities, aside from chronic HBV infection. * Co-infection with: * Current or past history of HCV * HIV * HDV * History of or suspected liver cirrhosis and/or evidence of cirrhosis as determined by: * both AST-Platelet Index (APRI) \>2 and FibroSure/FibroTest result \>0.7 * Liver biopsy (METAVIR Score F4) or Liver stiffness \>12 kPa * FibroScan TE score \>9.6 kPa and FibroTest score \>0.59 at Screening. * Diagnosed or suspected HCC. * History of: * malignancy within the past 5 years except of specific cancers that are cured by surgical resection * vasculitis or presence of symptoms and signs of potential vasculitis * extrahepatic disorders possibly related to HBV immune conditions * Positive (or borderline positive) ANCA at screening. * Low C3/C4 at screening AND evidence of past history or current manifestations of vasculitic/inflammatory/autoimmune conditions. * History of alcohol or drug abuse/dependence. * QTcF \>=450 msec. * Laboratory results as follows: * Serum albumin \<3.5 g/dL * GFR \<60 mL/min/1.73m\^2 * INR \>1.25 * PLT count \<140x10\^9/L * HGB \<10 g/dl * T Bil \>1.25xULN unless considered as clinically not significant by the Investigator * ACR \>=0.03 mg/mg * Medical history of hepatic decompensation. * Planned or previous liver transplantation. * Documented evidence of other currently active cause of hepatitis. * Any other clinical condition that might pose additional risk to the participant due to participation in the study. * Major congenital defects. * Recurrent history or uncontrolled neurological disorders or seizures. * History of any reaction or hypersensitivity likely to be exacerbated by any component of the study intervention(s). Prior/Concomitant therapy * Use of any investigational or non-registered product other than the study interventions within 30 days before the first dose of study interventions, or their planned use during the study. * Use of systemic cytotoxic agents, chronic antiviral agents or Chinese herbal medicines which may have activity against HBV within 6 months prior the study. * Currently taking, or took within 12 months of screening, any interferon-containing therapy. * Administration of adenovirus/adenovector-based or MVA-based vaccine within the last 12 months, except for adenovirus/adenovector-based COVID-19 vaccines that could be administered up to 30 days prior to the first study vaccine dose (applicable for all patients except for the patients in France) OR Administration of adenovirus/adenovector-based or MVA-based vaccine within the last 12 months (applicable for the patients in France only). * Planned administration/administration of a vaccine not foreseen by the study protocol within 14 days before the first dose and/or 30 days after the last dose of study intervention administration, with the exception of influenza vaccine that may be given at any time except within a 7-day period before or after each dose and COVID-19 vaccine that may be given at any time except within a 30-day period before or after each vaccine dose apart from COVID-19 mRNA based-vaccines that may be administered any time except for the period of 14 days before and 30 days after each study vaccine dose. * Administration of: * long-acting immune-modifying drugs at any time during the study * immunoglobulins and/or any blood products or plasma derivatives within 3 months before the first dose of study interventions or planned administration during the study * Chronic administration of immunosuppressants or other immune-modifying drugs within 3 months prior to the first study intervention (e.g. prednisone equivalent \>=20 mg/day; \>=10 mg/day applicable in Germany only). Inhaled and topical steroids are allowed. * Participants for whom immunosuppressive treatment is not advised. * Treatment with nephrotoxic drugs or competitors of renal excretion within 2 months prior to Screening or planned during the study. * Participants requiring anti-coagulation therapies. Prior/Concurrent clinical study experience * Concurrently participating in another clinical study, at any time during the study period, in which the participant has been/will be exposed to an investigational/a non-investigational intervention. * Previous participation in clinical trials with administration of either GSK3228836 or GSK3528869A. * Previous participation in a clinical study in which he/she has received an investigational product within the following time period prior to the first dosing day in the current study: 5 half-lives or twice the duration of the biological effect of the study treatment or 90 days. * Prior treatment with any other oligonucleotide/siRNA within 12 months prior to the first dosing day. Other exclusions: * Pregnant or lactating female. * Female planning to become pregnant/to discontinue contraceptive precautions. * Any study personnel or their immediate dependents, family, or household members. * History of/sensitivity to GSK3228836, or components thereof, or a history of drug or other allergy that contraindicates their participation.