HEPATITIS B Overview
Hepatitis B virus (HBV) virion, also known as Dane particle, contains an incomplete double-stranded DNA genome, a core protein (HBcAg), viral DNA polymerase (reverse transcriptase), and surface protein (HBsAg). HBV replication is unique in the sense that it utilizes reverse transcriptase enzyme to convert its pre-genomic RNA into genomic partially double-stranded DNA. HBV is the cause of what was formerly known as “serum hepatitis” just to distinguish it from “infectious hepatitis” (HAV). HBV is transmitted through sexual contact, sharing needles and syringes, injecting drugs, blood and blood-derived products and mother-to-child. The virus replicates (incubation period range 30-160, average 60-90 days) in the liver, however, the pathogenesis is mainly immune mediated, including serum sickness like rash, arthritis, and development of jaundice (symptoms like acute hepatitis A) due to circulating immune complexes that activate complement and cause liver damage. In addition, accumulation of immune complexes in the kidney results in renal damage. Antibody to HBsAg is protective and associated with resolution of the disease. About 90% of the patients resolve the infection after acute disease that may be asymptomatic; however, 10% of the patients develop chronic infection, probably due to insufficient cellular immunity. The chronicity is more than 90% if the virus is transmitted from mother-to-child. Chronicity may lead to cirrhosis of liver with an increased risk of HCC. Acute diagnosis is made by the presence of HBsAg and IgM to HBcAg and chronic by HBsAg (for more than 6 months) and IgG to HBcAg. Treatment for chronic infection includes alpha interferon and reverse transcriptase inhibitors. An effective subunit vaccine, HBsAg, is recommended for use in children starting at age 0 to 2 months and in adults given in 3 doses at 0, 1 and 6 months, which provides long-term protection.
Hepatitis B virus (HBV) is an enveloped DNA virus belonging to the family Hepadnaviridae (hepadnaviruses). It is unrelated to any other human virus; however, related hepatotropic agents have been identified in woodchucks, ground squirrels, and kangaroos. A schematic of the HBV is illustrated in Figure 13–4. The complete virion is a 42 nm spherical particle that consists of an envelope around a 27 nm core. The core comprises a nucleocapsid that contains the DNA genome.
Smallest known human DNA virus with respect to genome size
Schematic diagram of hepatitis B virion. A. The 42 nm particle is the “Dane particle” or the hepatitis B virus. B. The 22 nm particles are the filamentous and circular forms of hepatitis B surface antigen (HbsAg) or protein coat. (Reproduced with permission from Nester EW: Microbiology: A Human Perspective, 6th edition. 2009.)
The viral genome consists of partially double-stranded DNA with a short, single-stranded piece. It comprises 3200 nucleotides, making it the smallest known DNA virus with respect to genome size but capable of encoding surface (envelope) protein (hepatitis B surface antigen [HBsAg]), core (nucleocapsid) protein (hepatitis B core antigen [HBcAg]), DNA polymerase (reverse transcriptase), and HBx protein (a transcriptional activator). Closely associated with the viral DNA is a viral DNA polymerase, which has RNA-dependent DNA polymerase, DNA-dependent DNA polymerase, and RNase H activities (reverse transcriptase). Another component of the core is hepatitis B e antigen (HBeAg), which is a low–molecular-weight glycoprotein secreted from the infected cells. The virion has a lipid bilayer envelope containing the HBsAg, which is composed of one major and two other proteins. The complete virus particle is called a Dane particle.
✺ Enveloped DNA virus with viral DNA polymerase (reverse transcriptase) activity
Being a DNA virus, why does HBV need a reverse transcriptase enzyme?
Think ➱ Apply 13-2. Due to lack of accurate DNA synthesis from the HDV DNA template, it utilizes the pregenomic RNA as a template to synthesize its genomic DNA through the action of reverse transcriptase enzyme that makes both strands of DNA, although one strand is incomplete.
Aggregates of HBsAg are often found in great abundance in serum during infection. They may assume spherical or filamentous shapes with a mean diameter of 22 nm (Figure 13–4). HBV DNA can also be detected in serum and is an indication that infectious virions are present. In infected liver tissue, evidence of HBcAg, HBeAg, and hepatitis B DNA is found in the nuclei of infected hepatocytes, whereas HBsAg is found in cytoplasm. There are four major serotypes of HBV (adr, adw, ayr, ayw) based on HBsAg antigenic epitopes.
✺ HBsAg is produced in great abundance, presence indicates active infection
HBsAg found in cytoplasm of infected hepatocytes
Furthermore, there are eight hepatitis B genotypes (A-H) based on nucleotide sequence variation of HBV genome, which may be associated with different clinical outcomes. These genotypes vary in geographic distribution with genotype A primarily found in North America, Northern Europe, India, and Africa; genotypes B and C in Asia; genotype D in Southern Europe, Middle East, and India; genotype E in West and South Africa; genotype F in South and Central America; genotype G in the United States and Europe, and genotype H in Central America and California.
Four serotypes of HBsAg
Eight genotypes vary with geographic distribution
The replication of HBV involves a reverse transcription step, and, as such, is unique among DNA viruses (Figure 13–5). HBV has a specific tropism for the liver. However, the receptor for HBV and the mechanism of viral entry are not known. The attachment or adsorption of HBV to hepatocytes (liver cells) is mediated by the envelope protein (HBsAg) of the virus, probably by binding of HBsAg with polymerized human serum albumin or other serum proteins. After viral entry, the partially double-stranded DNA (incomplete) is transported to the nucleus. The double-stranded DNA is organized as two strands. One, a short strand, is associated with the viral DNA polymerase and is of positive polarity.
Partially incomplete double-stranded DNA is formed into a complete double-stranded DNA before transcription
Replication cycle of hepatitis B virus (HBV). HBV replication requires reverse transcription step, unique among DNA viruses. (Reproduced with permission from Nester EW: Microbiology: A Human Perspective, 6th edition. 2009.)
The complete or long strand is complementary and thus is of negative polarity. The partially incomplete strand is formed into a complete double-stranded, circular DNA, which is essential before the transcription can take place. Host RNA polymerase directs the transcription of viral mRNAs to encode early proteins, including HBcAg, HBeAg, and viral DNA polymerase as well as full-length RNA (pregenomic RNA). HBsAg is encoded later and associates with the membranes of endoplasmic reticulum or Golgi apparatus. HBcAg forms the core by enclosing the full-length, positive-sense viral pregenomic RNA along with viral DNA polymerase into maturing core particles late in the replication cycle. These full-length RNA strands form a template for a reverse transcription step in which negative-stranded DNA is synthesized. The RNA template strands are then degraded by ribonuclease H activity. A positive-stranded DNA is then synthesized, although this is not completed before virus maturation in which HBsAg-containing membranes of the endoplasmic reticulum or Golgi apparatus are wrapped over the nucleocapsid core, resulting in the variable-length, short, positive DNA strands found in the virions. The virions are released by exocytosis.
✺ Host RNA polymerase directs synthesis of viral mRNA
✺ Unique replication using a reverse transcriptase step among DNA viruses
✺ Full-length, pregenomic RNA converted to partially incomplete double-stranded DNA by viral DNA polymerase (reverse transcriptase)
Envelope membrane containing HBsAg wrapping from endoplasmic reticulum or Golgi apparatus
HBV DNA has also been found to integrate into the host chromosomes, especially in HBV-infected patients with hepatocellular carcinoma (HCC). However, the significance of integrated HBV DNA in viral replication is not known. Despite extensive attempts, HBV has not been successfully propagated in the laboratory. Humans appear to be the major host; however, as with hepatitis A, infection of subhuman primates has been accomplished experimentally.
Viral DNA integration occurs in some patients with HCC but not essential for viral replication
Humans are the major hosts
Hepatitis B infection is found worldwide. The WHO estimates that 240 million people are chronically infected with hepatitis B virus and more than 680 000 people die as a result of complications such as cirrhosis of liver and HCC worldwide. The prevalence rates varying markedly among countries with highest in sub-Saharan Africa and East Asia, where 5% to 10% of the adult population is chronically infected, and majority of them may be asymptomatic. In addition, Amazon area in South America, eastern and central areas of Europe, the Middle East and Indian subcontinent have high rates of chronicity. However, North America and Western Europe have less than 1% of their population chronically infected. About 10% of patients with HIV infection are chronic carriers of HBV.
Highest rates of HBV infection and chronicity in sub-Saharan Africa and East Asia
Other regions of the world such as Amazon area, eastern and central Europe, the Middle East and Indian subcontinent also have high rates of chronic infection
In the United States, CDC reports that at the end of 2014 there were approximately 850 000 to 2.2 million people chronically infected with hepatitis B. The rates of HBV infection have declined since 1990 due to HBV vaccination and has remained stable since 2009. In 2014, 2953 new acute HBV cases were reported, which are estimated to be 6.48 times higher (estimated cases 19 200, range 11 000-47 000) than the reported cases. About 200 to 300 of these patients die of acute fulminant hepatitis, and 5% to 10% of infected patients become chronic HBV carriers. An estimated, 3000 to 4000 people die yearly of hepatitis B-related cirrhosis, and 1000 to 1500 die of HCC. The virus is spread vertically, parenterally, and by sexual contact. Approximately 50% of infections in the United States are sexually transmitted, and the prevalence of HBsAg in serum is higher in certain populations, such as among men who have sex with men, patients on hemodialysis or immunosuppressive therapy, patients with Down syndrome, and injection drug users. Routine screening of blood donors for HBsAg and antibody to HBcAg (anti-HBcAg) has markedly decreased the incidence of postblood transfusion and postplasma products hepatitis B transmission. Multiple-pool blood products still cause occasional cases. Exposure to hepatitis viruses from direct contact with blood or other body fluids, probably through needlestick injuries, has resulted in a risk of hepatitis B infection in medical personnel. Attack rates are also high in the sexual partners of infected patients.
✺ About 50% of HBV infections in the United States are sexually transmitted
Needlestick transmission is a risk for healthcare workers
Hepatitis B infection of infants does not appear to be transplacentally transmitted to the fetus in utero, but is acquired during the birth process by the swallowing of infected blood or fluids or through abrasions. The rate of virus acquisition is high (up to 90%) in infants born to mothers who have acute hepatitis B infection or are carrying HBsAg and HBeAg. Most infants do not develop clinical disease; however, infection in the neonatal period is associated with failure to produce antibody to HBsAg and cell-mediated immune responses probably due to an immature immune system, which allows chronic carriage to occur in more than 90% of the infected neonates/infants.
Vertical transmission usually occurs during birth process
✺ Chronicity extremely high in vertically infected infants
HCC has been strongly associated with persistent carriage of HBV by serologic tests and by detection of viral nucleic acid sequences integrated in tumor cell genomes. In many parts of Africa and Asia, primary liver cancer accounts for 20% to 30% of all types of malignancies, but in North and South America and in Europe, it is only 1% to 2%. The estimated risk of developing the malignancy for persons with chronic HBV is increased to between 10-fold and more than 300-fold in different populations. The risk of HCC further increases in patients with chronic hepatitis B infection and high viral loads.
✺ Strong association between HBV chronic infection and HCC
In the past, hepatitis B was known as posttransfusion hepatitis or as hepatitis associated with the use of illicit parenteral drugs (serum hepatitis). However, over the last few years it has become clear that the major mode of acquisition is through close personal contact with body fluids of infected individuals. HBsAg has been found in most body fluids, including saliva, semen, and cervical secretions. Under experimental conditions, as little as 0.0001 mL of infectious blood has produced infection. Transmission is therefore possible by vehicles such as inadequately sterilized hypodermic needles and instruments used in tattooing and ear piercing.
Virus found in blood, saliva, and semen
The factors determining the clinical manifestations of acute hepatitis B are largely unknown; however, some appear to involve immunologic responses of the host. The serum sickness-like rash and arthritis that may precede the development of symptoms and jaundice appear to be related to circulating immune complexes that activate the complement system. In addition, accumulation of these immune complexes in the kidney results in renal damage. Antibody to HBsAg is protective and associated with resolution of the disease. Cellular immunity also may be important in the host response because patients with insufficient T-lymphocyte function have a high incidence of chronic infection with HBV. However, CTLs cause damage to liver by destroying infected cells. Antibody to HBcAg, which appears during infection, is present in chronic carriers with persistent hepatitis B virion production and does not appear to be protective.
✺ Immunologic factors contribute to pathogenicity
✺ Serum sickness-like rash and arthritis precede development of symptoms
✺ Antibody to HBsAg is protective in acute hepatitis
✺ Cellular immunity plays an important role in resolution of the disease
✺ Defects in cellular immunity results in high incidence of chronic infection
The morphologic lesions of acute hepatitis B resemble those of other hepatitis viruses. In chronic active hepatitis B, the continued presence of inflammatory foci of infection results in necrosis of hepatocytes, collapse of the reticular framework of the liver, and progressive fibrosis. The increasing fibrosis can result in the syndrome of postnecrotic hepatic cirrhosis (Figure 13–6).
✺ Chronic infection leads to progressive fibrosis and cirrhosis
Cirrhosis of liver in chronic hepatitis B infection (HBV). This is a needle biopsy of Masson trichrome stain that shows cirrhotic nodules and portion of nodules separated by fibrous scars. (Reproduced with permission from Connor DH, Chandler FW, Schwartz DQ, et al: Pathology of Infectious Diseases. Stamford CT: Appleton & Lange, 1997.)
Why HBV pathogenesis is more immune-mediated than viral-mediated?
Integrated hepatitis B viral DNA can be found in nearly all HCCs. The virus has not been shown to possess a transforming gene but may well activate a cellular oncogene. It is also possible that the virus does not play a direct molecular role in oncogenicity, because the natural history of chronic hepatitis B infection involves cycles of damage or death of liver cells interspersed with periods of intense regenerative hyperplasia. This significantly increases the opportunity for spontaneous mutational changes that may activate cellular oncogenes. HBV transcriptional transactivator protein, HBx, is known to activate the Src kinase, which may influence HBV-induced carcinogenesis. HBx protein has been shown to interact with tumor suppressor gene, p53, which may result in the development of oncogenesis and HCC. Whatever the mechanisms may be, the association between chronic hepatitis B infection and HCC is clear, and liver cancer is a major cause of disease and death in countries in which chronic hepatitis B infection is common. The proven success of combined active and passive immunization in aborting hepatitis B infection in infancy and childhood makes HCC a potentially preventable disease.
Mechanism of HCC development is not clearly known
✺ Strong association between chronic viral infection and HCC
The clinical picture of hepatitis B is highly variable. The incubation period may be as brief as 30 days or as long as 180 days (mean approximately 60-90 days). Acute hepatitis B is usually manifested by the gradual onset of fatigue, loss of appetite, nausea and pain, and fullness in the right upper abdominal quadrant. Early in the course of disease, pain and swelling of the joints and occasional frank arthritis may occur. Some patients develop a rash. With increasing involvement of the liver, there is increasing cholestasis, and hence clay-colored stools, darkening of the urine, and jaundice. Symptoms may persist for several months before finally resolving.
Average incubation period 60 to 90 days; range 30 to 180 days
✺ Chronic hepatitis is most common with infection in early infancy or childhood
In general, the symptoms associated with acute hepatitis B are more severe and more prolonged than those of hepatitis A; however, anicteric disease and asymptomatic infection occur. The infection-to-disease ratio, which varies according to patient age and method of acquisition, has been estimated to be approximately 3:1. Fulminant hepatitis, leading to extensive liver necrosis and death, develops in less than 1% of the cases. One important difference between hepatitis A and hepatitis B is the development of chronic hepatitis, which occurs in approximately 10% of all patients with hepatitis B infection, with a much higher risk for newborns (~90%), children (~50%), and the immunocompromised. In immunocompetent adults, the strong cellular immune response results in acute hepatitis and only rarely (~1%) in chronic hepatitis. Chronic infection is associated with ongoing replication of virus in the liver and usually with the presence of HBsAg in serum. Chronic hepatitis may lead to cirrhosis, liver failure, or HCC in up to 25% of the patients.
Why does HBV cause higher chronicity in infected neonates/infants than adults?
Think ➱ Apply 13-3. Since HBV replication in hepatocytes is non-cytopathic, the damage to liver starts with the cytotoxic T cells killing infected cells followed by recruitment of mononuclear cells and production of proinflammatory cytokines causing further liver damage. Formation of immune complexes also causes liver and extrahepatic damage.
The nomenclature of hepatitis B antigens and antibodies is shown in Table 13–2 and the sequence of their appearance is shown in Figure 13–7. During the acute episode of disease, when there is active viral replication, large amounts of HBsAg and HBV DNA can be detected in the serum, as can fully developed virions and high levels of DNA polymerase and HBeAg. Although HBcAg is also present, but antibody against it (anti-HBc) invariably occurs and prevents HBcAg detection. Upon resolution of acute hepatitis B, HBsAg and HBeAg disappear from serum with the development of antibodies (anti-HBs and anti-HBe) against them. There is small period “window period” or equivalence zone characterized by the disappearance of HBsAg and before the appearance of anti-HBs. During this window period, HBsAg and anti-HBs are absent but anti-HBc (IgM) is present (anti-Hbe may also be present). The development of anti-HBs is associated with elimination of infection and protection against reinfection. Anti-HBc is detected early in the course of disease and persists in serum for years. It is an excellent epidemiologic marker of infection, but is not protective. The laboratory diagnosis of acute hepatitis B infection is best made by demonstrating the presence of HBsAg and IgM antibody to HBcAg in serum, since this antibody disappears within 6 months of the acute infection. Almost all patients who develop jaundice are anti-HBc IgM-positive at the time of clinical presentation. Past infection with hepatitis B is best determined by detecting IgG antibody to HBcAg, HBsAg, or both, whereas vaccine induces only antibody to HBsAg. While the HBV antigens and antibodies are demonstrated by enzyme immune assay, HBV DNA is detected by PCR.
✺ Acute HBV infection is demonstrated with appearance of HBsAg and IgM antibody to HBcAg in serum
✺ Appearance of antibody to HBsAg signals elimination of infection
✺ Window period has neither HBsAg nor antibody to HBsAg but antibody to HBcAg (IgM) is present
TABLE 13–2Nomenclature for Hepatitis B Virus Antigens and Antibodies ||Download (.pdf) TABLE 13–2 Nomenclature for Hepatitis B Virus Antigens and Antibodies
|ABBREVIATION ||DESCRIPTION |
|HBV ||Hepatitis B virus; 42 nm, double-stranded DNA virus; Dane particle |
|HBsAg ||Hepatitis B surface antigen; found on surface of virus; formed in excess and seen in serum as 22 nm spherical and tubular particles; four subdeterminants (adw, ayw, adr, and ayr) identified |
|HBcAg ||Core antigen (nucleocapsid core); found in nucleus of infected hepatocytes by immunofluorescence |
|HBeAg ||Glycoprotein; associated with the core antigen; used epidemiologically as marker of potential infectivity; seen only when HBsAg is also present |
|Anti-HBs ||Antibody to HBsAg; correlated with protection against and/or resolution of disease; used as a marker of past infection or vaccination |
|Anti-HBc ||Antibody to HBcAg; seen in acute infection and chronic carriers; anti-HBc IgM used as indicator of acute infection; anti-HBc IgG used as a marker of past or chronic infection; apparently not important in disease resolution; does not develop in response to vaccine |
|Anti-HBe ||Antibody to HBeAg |
Sequence of appearance of viral antigens and antibodies in acute self-limiting cases of hepatitis B. Anti-HBc, antibody to hepatitis B core antigen; anti-HBe, antibody to HBeAg; anti-HBs, antibody to HBsAg; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen.
Think ➱ Apply 13-4. The higher rate of chronicity in neonates/infants than adults is most likely due to relative immaturity of the immune system of the neonates/infants, which is unable to contain HBV replication.
In patients with chronic hepatitis B, evidence of viral persistence can be found in serum (Figure 13–8). HBsAg can be detected throughout the active disease process, and anti-HBs does not develop, which probably accounts for the chronicity of the disease. However, anti-HBc (IgG) is detected. Two types of chronic hepatitis can be distinguished. In one, HBsAg is detected, but not HBeAg; these patients usually show progressive liver dysfunction. In the other, both antigens are found; development of antibody to HBeAg is associated with clinical improvement. Chronic infection with hepatitis B is best detected by persistence of HBsAg in blood for more than 6 to 12 months. Progression of liver disease is associated with more than 1000 IU/mL (5600 copies/mL) of HBV DNA. Persons with levels lower than 1000 IU/mL and normal liver function have a low risk of progression. HBV DNA is monitored to determine the efficacy of antiviral treatment. Moreover, a new test has been recently approved that would quantify the levels of HBsAg in HBV infected patients, which could be used as a predictive marker for antiviral efficacy, disease progression, risks of liver damage, and sign of recovery.
✺ Chronic infection associated with HBsAg persistence and no development of antibody to HBsAg. IgG antibody to HBcAg present
HBV DNA measured to determine antiviral efficacy during treatment
New quantitative HBsAg test approved
Sequence of appearance of viral antigens and antibodies in chronic active hepatitis B. Antibodies to HBsAg and HBeAg are not detected. Anti-HBc, antibody to hepatitis B core antigen; HBeAg, hepatitis B e antigen; HBsAg, hepatitis B surface antigen.
There is no specific treatment recommended for acute hepatitis B. A high-calorie diet is desirable. Treatment should be considered for patients with rapid deterioration of liver function, cirrhosis or complications such as ascites, hepatic encephalopathy, or hemorrhage as well as those who are immunosuppressed. For chronic hepatitis B diseases, pegylated or regular interferon-α provides benefit in some patients. Lamivudine (3TC), a potent inhibitor of HIV reverse transcriptase, and other nucleoside analogs (entecavir, telbivudine) as well as certain nucleotide analogs (adefovir, tenofovir) are active against hepatitis B. These antivirals inhibit viral replication and may reduce viral load but do not cure HBV infection.
No specific treatment for acute infection
Interferon and nucleoside and nucleotide analogs (reverse transcriptase inhibitors) are of benefit in chronic infection
Screening of blood and plasma product donors for HBsAg, anti-HBcAg, and HBV DNA has greatly reduced the incidence of hepatitis B in recipients. Similarly, screening pregnant women and treatment of exposed newborns with hepatitis B immune globulin (HBIG) and HBV vaccine have significantly reduced vertical transmission. Safe sexual practices and avoidance of needlestick injuries or injection drug use are approaches to diminishing the risk of hepatitis B infection. Both active prophylaxis and passive prophylaxis against hepatitis B infection can be accomplished. Most preparations of ISG contain only moderate levels of anti-HBs; however, specific HBIG with high titers of hepatitis B antibody is now available. HBIG is prepared from sera of subjects who have high titers of antibody to HBsAg, but are free of the antigen itself. Administration of HBIG soon after exposure to the virus greatly reduces the development of symptomatic disease. Postexposure prophylaxis with HBIG should be followed by active immunization with vaccine.
Postexposure treatment with HBIG temporarily reduces risk
Purified inactivated HBsAg protein (HBsAg subunit vaccine) from chronic carriers has been available for several years. This was developed by purification and inactivation of HBsAg from the blood of HBV-infected chronic carriers, but it is no longer in use. The current vaccine (ENGERIX-B, RECOMBIVAX-HB) is a recombinant product derived from HBsAg expressed in yeast. Excellent protection has been shown in studies of men who have sex with men and in medical personnel. These groups and others, such as laboratory workers, injection drug users, travelers to endemic areas, persons at risk for sexually transmitted diseases, and those in contact with patients who have chronic hepatitis B, should receive hepatitis B vaccine as the preferred method of preexposure prophylaxis. Recently, immunization of newborns, all children, and adolescents has been recommended. Three intramuscular doses (at 0, 1, and 6 months) are given to achieve maximum titer. Protection is long term (approximately 20 years) but may not be lifelong. Neonates receive the first dose soon after birth and before leaving the hospital.
Some people do not respond to HBV vaccine. Several factors could be attributed to this nonresponse such as dose, schedule, injection site, age (older adults), obesity and chronic illness. People who fail to seroconvert with the first series of HBV vaccine should be vaccinated for a second three-dose series in the deltoid muscle. Failure to respond after six doses of HBV vaccine may be because of persistent HBV infection, which should be evaluated. In addition, people who do not respond to vaccine should be given HBIG for prophylaxis and/or for other known risks.
Recombinant (HBsAg) vaccine recommended for all children and high-risk persons
Protection is long term, probably not lifelong
Several combination vaccines are also available. These include COMVAX (hepatitis B-Haemophilus influenzae conjugate vaccine, cannot be given before 6 weeks or after 71 months), PEDIARIX (hepatitis B, diphtheria, tetanus, acellular pertussis, and inactivated polio, cannot be given before 6 weeks or after 7 years), and TWINRIX (hepatitis A and hepatitis B is recommended at the age of 18 years or above).
Combination vaccines available with age restrictions for delivery
A combination of active and passive immunization is the most effective approach to prevent neonatal acquisition and chronic carriage in the neonate. Routine screening of pregnant women for the presence of HBsAg is recommended. Infants born to those who are positive should receive HBIG in the delivery room followed by three doses of hepatitis B vaccine beginning 24 hours after birth. A similar combination of passive and active immunization is used for unimmunized persons who have been exposed by needlestick or similar injuries. The procedure varies depending on the hepatitis B status of the “donor” case linked to the injury.
Combination of HBIG and vaccine significantly reduces vertical transmission