Hepatitis B immunoglobulin (HBIG) injections contain antibodies that provide immediate but temporary protection against the hepatitis B virus (HBV). They work by neutralizing circulating virus particles and preventing infection of liver cells.
HBIG injections play a key role in preventing hepatitis B infection in certain high-risk situations when exposure to HBV has occurred.
This article provides an overview of HBIG, its efficacy, and guidelines on when HBIG injections are recommended for preventing hepatitis B.
Overview Of HBIG
HBIG contains polyclonal antibodies (immunoglobulins) obtained from pooled plasma of individuals with immunity to hepatitis B.
Hence, it provides passive immunity and immediate protection, unlike vaccines which take time to develop immunity.
How Does It Work?
Being antibodies against HBV surface antigen, HBIG neutralizes circulating virus. This prevents the virus from entering and infecting liver cells.
Maximum viral neutralization occurs when HBIG is administered soon after exposure.
HBIG provides rapid, short-term protection against hepatitis B. When administered correctly, HBIG is 75-90% effective in preventing HBV infection from a known exposure.
Maximum protection occurs when the first dose is given within 24 hours, though some effect persists for 7 days after exposure. Protection lasts for 3-6 months.
HBIG alone does not provide long-lasting immunity against future HBV exposures. Hence, it is typically administered along with the first dose of the hepatitis B vaccine to confer both immediate and long-term protection.
Indications For HBIG
🔹 Newborns of HBV-infected mothers
Infants born to HBV-positive mothers are at high risk of getting infected during childbirth. Giving HBIG along with vaccine at birth is 85-95% effective in preventing transmission from the mother.
🔹 Needlestick injuries
HBIG is recommended after needlestick or sharps injuries if the source individual is HBV positive. When given within 24 hours along with the vaccine, it reduces the risk of developing hepatitis B by 75%.
🔹 Sexual exposure
Recent unprotected sex with an HBV-infected partner warrants HBIG along with a vaccine for protection. An alternative preventive strategy is the initiation of hepatitis B antiviral treatment.
🔹 Household exposure
For an unvaccinated individual exposed to a household member with acute HBV infection, HBIG and vaccine are advised, especially if exposure to blood or body fluids occurred.
🔹 Liver transplant recipients
Recipients of liver transplants from HBV-positive donors are given HBIG at transplant, followed by daily/weekly doses for several months to prevent HBV recurrence.
🔹 Hepatitis B surface antigen-positive dialysis patients.
HBIG injections are sometimes used in hepatitis B patients on dialysis to help reduce the risk of transmission.
Timing, Dose, And Administration
HBIG should be given as soon as possible after a known HBV exposure, preferably within 24 hours for maximum effectiveness.
In high-risk exposures, the first dose is often doubled. For a newborn, the recommended HBIG dose is 0.5 mL intramuscularly within 12 hours of birth.
For continuing protection after a liver transplant, HBIG dosing protocols vary from daily to monthly injections based on risk. The aim is to maintain protective antibody levels.
HBIG is given by intramuscular or intravenous injection. Local pain and tenderness may occur at the injection site.
Limitations And Precautions
- Does not provide long-term protection
- Not effective once hepatitis B infection has already occurred
- Repeat dosing is required in certain cases
- Allergic reactions are possible in susceptible individuals
- Small infection risk from plasma-derived product
- May interfere with response to live vaccines
- Use cautiously in IgA-deficient patients
- Avoid in the previous history of anaphylaxis to immune globulins
In summary, HBIG injections provide short-term, passive immunoprophylaxis against hepatitis B, giving immediate but temporary protection.
When combined with vaccination, HBIG is highly effective in preventing HBV infection following high-risk exposures like birth to an infected mother, needlestick injury, sexual contact, etc. Exact guidelines exist on appropriate timing, dosage, and administration.
While limited in duration, HBIG serves a vital role in hepatitis B prevention strategies along with vaccines, antiviral therapy, and long-term immunization.
With a sound understanding of its applications, healthcare providers can judiciously use HBIG to provide immediate immunity and limit hepatitis B transmission following specific exposures.