hepatitis a/​b vaccine

Action and Spectrum

Actions and Spectrum: 

The hepatitis A and B vaccines work by stimulating the body’s immune system to produce antibodies against the hepatitis A and B viruses. These antibodies protect the body from future infection with these viruses. The hepatitis A vaccine contains inactivated virus particles that cannot cause disease but can stimulate an immune response.

When the vaccine is administered, the body recognizes the viral particles as foreign and produces antibodies against them. If the person is exposed to the hepatitis A virus in the future, the pre-existing antibodies can neutralize the virus and prevent infection. 

The hepatitis B vaccine contains a part of the hepatitis B virus called the surface antigen. When the vaccine is administered, the body recognizes the surface antigen as foreign and produces antibodies against it. If the person is exposed to the hepatitis B virus in the future, the pre-existing antibodies can neutralize the virus and prevent infection. 

Drug Interaction

Adverse Reaction

Frequency defined 

>10% 

Soreness (37%) 

Fatigue (14%) 

Headache (22%)  

1-10% 

Diarrhea (5%) 

Fever (4%) 

Redness (8%) 

Nausea (4%) 

Swelling (4%) 

Black Box Warning

Contraindication / Caution

Contraindications/caution: 

Contraindications: 

• Previous severe allergic reaction to a vaccine component or after a previous dose of the vaccine. 
• Moderate or severe acute illness with or without fever. In such cases, vaccination should be postponed until after the illness has resolved. 
• Pregnancy: The safety of the hepatitis A and B vaccines in pregnant women has not been fully established. However, there is no evidence to suggest that the vaccine causes harm to the fetus, and the benefits of vaccination may outweigh the risks in certain circumstances. 
• Severe immunodeficiency: Vaccination may be contraindicated in individuals with severe immunodeficiencies, such as those with advanced HIV infection or those undergoing chemotherapy or radiation therapy. 
• Known hypersensitivity to yeast: Some formulations of the hepatitis B vaccine contain yeast proteins and should not be given to individuals with a known hypersensitivity to yeast. 

Caution: 

• Bleeding disorders: Individuals with bleeding disorders, such as hemophilia, should receive the vaccine with caution to prevent bleeding at the injection site. 
• Immunocompromised individuals: The vaccine may be less effective in individuals with weakened immune systems, such as HIV, or receiving immunosuppressive therapy. 
• Age considerations: The vaccines are safe and effective in individuals of all ages, but the dosing schedule may differ depending on age and vaccine type. 
• Chronic liver disease: Individuals with chronic liver disease may require additional vaccine doses for adequate protection. 
• Adverse reactions: Like all vaccines, the hepatitis A and B vaccines may cause adverse reactions, such as injection site pain, fever, headache, and fatigue. These reactions are usually mild and resolve on their own. 

Pregnancy / Lactation

Pregnancy consideration: The safety of the hepatitis A and B vaccines in pregnant women has not been fully established. However, there is no evidence to suggest that the vaccine causes harm to the fetus, and the benefits of vaccination may outweigh the risks in certain circumstances. 

Lactation: Excretion of the drug in human breast milk is unknown 

Pregnancy category: 

Category A: well-controlled and Satisfactory studies show no risk to the fetus in the first or later trimester.   

Category B: there was no evidence of risk to the fetus in animal studies, and there were not enough studies on pregnant women. 

Category C: there was evidence of risk of adverse effects in animal reproduction studies, and no adequate evidence in human studies must take care of potential risks in pregnant women.    

Category D: adequate data with sufficient evidence of human fetal risk from various platforms, but despite the potential risk, and used only in emergency cases for potential benefits.    

Category X: Drugs listed in this category outweigh the risks over benefits. Hence these categories of drugs need to be avoided by pregnant women.    

Category N: There is no data available for the drug under this category 

Pharmacology

Pharmacology: 

• The hepatitis A and B vaccines are biological products that stimulate the body’s immune system to produce antibodies against the hepatitis A and B viruses. They are administered by injection and are composed of either inactivated virus particles or a part of the surface antigen virus. 

• The hepatitis A vaccine comprises inactivated virus particles that cannot cause disease but can stimulate an immune response. The vaccine is administered in two doses, with the second dose given 6 to 12 months after the first. The vaccine provides long-term protection against hepatitis A; booster doses may be recommended after several years to maintain immunity. 

• The hepatitis B vaccine contains a part of the hepatitis B virus called the surface antigen. The vaccine is administered in two to three doses, depending on the vaccine type and age of the individual. The vaccine provides long-term protection against hepatitis B; booster doses may be recommended after several years to maintain immunity. 

• Both vaccines have been extensively studied and are considered safe and effective. The vaccines have high efficacy rates in preventing infection with their respective viruses and have been shown to reduce the incidence of hepatitis A and B infections in vaccinated populations. 

Pharmacodynamics: 

• The pharmacodynamics of the hepatitis A and B vaccines involve the interaction between the vaccine components and the body’s immune system. 

• When the vaccine is administered, the inactivated virus particles or surface antigens stimulate the immune system to produce specific antibodies against the hepatitis A or B virus. These antibodies are responsible for neutralizing the virus and preventing infection. 

• The production of antibodies is initiated by immune cells called B cells, which recognize the vaccine components as foreign and activate a complex cascade of immune responses. The activated B cells differentiate into plasma cells, which produce and release significant quantities of antibodies specific to the vaccine components. 

• Over time, the level of antibodies in the bloodstream gradually declines, which may reduce the level of protection against infection. Therefore booster doses may be recommended after several years to maintain immunity. 

Pharmacokinetics: 

Absorption 

The hepatitis A and B vaccines are administered by intramuscular injection, which ensures direct and complete absorption of the vaccine components into the bloodstream. 

Distribution 

After absorption, the vaccine components are distributed throughout the body, stimulating the immune system to produce antibodies against the viruses. 

Metabolism 

The hepatitis A and B vaccines are not metabolized by the body because they contain inactivated virus particles or surface antigens that enzymes cannot break down. 

Elimination and Excretion 

The body does not excrete the hepatitis A and B vaccines because they are not metabolized or transformed into other compounds. 

Adminstartion

Administration: 

The hepatitis A and B vaccines are administered by intramuscular injection in the upper arm or thigh. The specific administration guidelines may vary depending on the vaccine type and age of the individual, but generally, the following steps are followed: 

• Preparation: The healthcare provider will ensure the vaccine is stored correctly and inspect the vial for damage or defects. The vaccine will be brought to room temperature and gently shaken to ensure the contents are evenly mixed. 

• Injection site preparation: The site will be cleaned with an antiseptic solution, and the healthcare provider will ensure the area is dry before administering the vaccine. 

• Injection: The healthcare provider will use a sterile syringe and needle to administer the vaccine into the muscle tissue. The vaccine should not be injected into the veins, subcutaneous tissue, or fat layers. 

• Post-injection care: The healthcare provider will observe the individual for immediate adverse reactions. The individual should remain at the clinic or healthcare facility for at least 15 minutes to monitor for any signs of an allergic reaction. 

• Follow-up: The individual will typically receive a second dose of the vaccine 6 to 12 months after the first dose. Booster doses may be recommended after several years to maintain immunity, particularly in individuals at high risk of infection. 

Patient Information Leaflet

Patient information leaflet 

Generic Name: hepatitis A and B vaccine 

Why do we use hepatitis A and B vaccines? 

The primary use of the hepatitis A and B vaccines is to prevent infection with the hepatitis A and B viruses. These vaccines are highly effective in preventing hepatitis A and B infections and the severe health consequences associated with these infections. 

The hepatitis A vaccine is recommended for individuals who may be at risk of contracting the virus, including: 

• Individuals traveling to areas with high rates of hepatitis A 
• Men who have sex with men 
• Injection or non-injection drug users 
• Individuals with chronic liver disease 
• Individuals with clotting factor disorders 

The hepatitis B vaccine is recommended for all infants and children, as well as adults who may be at risk of contracting the virus, including: 

• Healthcare workers 
• Individuals with multiple sex partners 
• Injection or non-injection drug users 
• Individuals with chronic liver disease 
• Individuals with HIV/AIDS 

The hepatitis A and B vaccines are also recommended for individuals exposed to the viruses or at increased risk of exposure due to their occupation or lifestyle. Additionally, the vaccines may be recommended for individuals with certain medical conditions, such as chronic kidney disease or hepatitis C, to protect against further liver damage.