Hepatitis A

What is Hepatitis A? 

Hepatitis A is a highly contagious viral infection that causes liver inflammation. It is caused by the Hepatitis A virus (HAV), an RNA virus that primarily spreads through the fecal-oral route, meaning it is transmitted when someone ingests food or water contaminated with feces from an infected person (1). 

How is Hepatitis A Contracted? 

Hepatitis A spreads through the fecal-oral route, typically via contaminated food or water. Once ingested, it travels to the liver, where it replicates. Hepatitis A can be detected in the blood and feces about 12 days after infection and may remain present for up to three weeks. Transmission requires ingestion of fecal matter from an infected person. 

Common sources of contamination include daycares, restaurants, bodies of water (due to inadequate sewage management), and areas with poor sanitation practices (1). 

Hepatitis A Symptoms 

MILD 

Hepatitis A may cause  

• Fatigue 
• Malaise 
• Low-grade fever that can reach 102°F and typically lasts 2–3 days 

MODERATE 

Hepatitis A may cause  

• Fatigue 
• Malaise 
• Low-grade fever up to 102°F lasting 2–3 days 
• Diarrhea 
• Nausea 
• Jaundice (yellowing of the skin) 

SEVERE 

Adults may experience more severe symptoms, including  

• Enlarged liver 
• Liver damage, or, in rare cases, acute liver failure 

Complications of Hepatitis A can include hospitalization in 11–22% of cases. Before the introduction of the vaccine in 1996, the death rate was 2–5 per 1,000 infected individuals. In the past 10 years, no deaths have been reported (1). 

Conventional Treatment for Hepatitis A 

There is no specific medical treatment for Hepatitis A, and the virus must run its course; however, those who contract it develop lifelong immunity (2). 

When is the Hepatitis A Vaccine Given? 

The Hepatitis A vaccine (HAV) is given in 2 doses: at 12 months and 18 months (3). 

For more information, see:  CDC/Alternative Vaccine Schedules 

Efficacy of the Hepatitis A Vaccine 

One dose 

1 dose of HAV vaccine is 

• >95% effective in adults 
• >97% effective in children (4)

Two doses 

2 doses of HAV vaccine are 

• 100% effective in adults 
• 100% effective in children (4) 

CDC Pink Book – Hepatitis A 

How long does the Hepatitis A Vaccine last? 

It is unknown how long a vaccinated person remains protected against Hepatitis A, as the HAV vaccine has only been available since 1995–1996, and the duration of protection has not been fully established (5). 

Ingredients in the Injected Hepatitis A Vaccines 

Below is an overview of the components found in HAV products. 

VAQTA (Merck)

• The hep A virus (whole, dead virus) 
• Aluminum – 225 mg/dose 
• Saline solution 
• Residual proteins and DNA from the human embryo cell line 
• Traces of cow blood proteins (albumin) to nourish the human cell line 
• Formaldehyde 
• Sodium borate (to decrease acidity) 
• “Other residual chemicals at a level of 10 parts per billion” (the actual chemicals aren’t listed) 

HAVRIX (GlaxoSmithKline)

• The hep A virus (whole, dead virus) 
• Aluminum – 250 mcg/dose 
• Saline solution 
• 2-phenoxyethanol (0.5 percent of the vaccine solution) 
• Amino acids (0.3 percent of the vaccine solution), which are used to nourish the human cells 
• Polysorbate 20 (25 micrograms) 
• Formalin (50 micrograms) 
• Residual proteins from the human cells (Residual DNA isn’t listed, but it may be as it is in VAQTA.) 
• Neomycin (extremely minute traces), an antibiotic used to keep the cell culture sterile

Note: Adults 19 years and older receive one dose of adult formulation (50 U per dose) with a booster dose 6 to 18 months after the first dose (this means double the dose of the ingredients above) (6). 

CONTROVERSIAL INGREDIENTS IN THE HEPATITIS A VACCINES 

• Hepatitis A virus – This is the inactivated form of the Hepatitis A virus used to stimulate an immune response without causing infection. Since it is not a live virus, it cannot replicate or cause disease. 
• Aluminum – Aluminum salts are commonly used in vaccines as adjuvants to enhance the immune response. While generally considered safe, some people question the long-term effects of aluminum exposure, particularly in infants. 
• 2-Phenoxyethanol – A preservative to prevent bacterial contamination. It has been scrutinized due to concerns about toxicity at high doses. 
• Polysorbate 20 – An emulsifier that helps keep the vaccine components mixed. Some concerns exist about potential effects on cell membranes. 
• Formalin – Also known as formaldehyde, this is used to inactivate the virus. While formaldehyde is a known toxin in high amounts, the trace amounts in vaccines are far lower than what the body naturally produces and are not considered harmful. 
• Residual proteins and DNA from human embryo cell lines – Some vaccines use human cell lines to grow the virus, and small amounts of DNA or proteins may remain in the final product. This is controversial among those who oppose using fetal-derived cell lines in medical research. 
• Traces of cow blood proteins (albumin) – Used to nourish human cell cultures during vaccine production, albumin is a common protein found in blood. Some people avoid it due to concerns about animal-derived vaccine ingredients, particularly for religious or ethical reasons. 
• Sodium borate – Used to balance the pH of the vaccine. It has been questioned because it is toxic in large quantities. 
• Neomycin – Is an antibiotic to prevent bacterial contamination during vaccine production. Some individuals with antibiotic allergies may be concerned, but the traces present in vaccines are usually too small to cause reactions. 
• Other residual chemicals – The unspecified chemicals listed at very low levels raise questions about transparency, but at such minute concentrations, they are unlikely to pose health risks. 

If you would like specific information, including studies, regarding each ingredient, see Vaccine Ingredients. 

Hepatitis A Vaccine FDA Package Inserts 

• VAQTA (Merck) 
• HAVRIX (GlaxoSmithKline) 

Controversy and the Hepatitis A Vaccine 

Nearly all children under six who contract Hepatitis A show no symptoms except for a possible low-grade fever and mild diarrhea for a few days.  

Older children may develop mild symptoms, but severe illness is rare. The most serious cases occur in adults, meaning vaccinating young children primarily protects the adult population.  

According to the CDC Pink Book on Hepatitis A, “Children play a key role in transmission, as their infections often go unnoticed, making them a potential source of spread, particularly to household members and close contacts” (4). 

Hepatitis A Vaccine Reactions 

SIGNS TO LOOK FOR: 

• Fatigue 
• Fever >99.5°F (37.5°C) 
• Induration, redness, and swelling of the injection site 
• Malaise (6) 

KNOWN SEVERE REACTIONS: 

• Safety studies reported seizures in 1% of children 12-23 months of age (7) 

POSTMARKETING SURVEILLANCE: 

VAQTA 

The following additional adverse events, regardless of causality, have been reported during postmarketing use of VAQTA (6): 

• Eye disorders: Conjunctivitis  
• Gastrointestinal disorders: Constipation; vomiting  
• General disorders and administration site conditions: Injection-site bruising; injection-site ecchymosis, thrombocytopenia 
• Infections and infestations: Otitis media, nasopharyngitis, rhinitis, viral infection, croup, pharyngitis streptococcal, laryngotracheobronchitis, viral exanthema, gastroenteritis viral, roseola  
• Metabolism and nutrition disorders: Anorexia  
• Psychiatric disorders: Insomnia, crying  
• Respiratory, thoracic and mediastinal disorders: Cough, nasal congestion, respiratory congestion  
• Skin and subcutaneous tissue disorders: Rash vesicular, measles-like/rubella-like rash, varicella-like rash, rash morbilliform 
• Nervous system disorders: Guillain-Barré syndrome; cerebellar ataxia; encephalitis. 

HAVRIX 

The following additional adverse events, regardless of causality, have been reported during postmarketing use of HAVRIX (7): 

• Infections and Infestations: Rhinitis. 
• Blood and Lymphatic System Disorders: Thrombocytopenia. 
• Immune System Disorders: Anaphylactic reaction, anaphylactoid reaction, serum sickness-like syndrome. 
• Nervous System Disorders: Convulsion, dizziness, encephalopathy, Guillain-Barré syndrome, hypoesthesia, multiple sclerosis, myelitis, neuropathy, paresthesia, somnolence, syncope. 
• Vascular Disorders: Vasculitis. 
• Respiratory, Thoracic, and Mediastinal Disorders: Dyspnea. 
• Hepatobiliary Disorders: Hepatitis, jaundice. 
• Skin and Subcutaneous Tissue Disorders: Angioedema, erythema multiform, hyperhidrosis. 
• Congenital, Familial, and Genetic Disorders: Congenital anomaly. 
• Musculoskeletal and Connective Tissue Disorders: Musculoskeletal stiffness. 
• General Disorders and Administration Site Conditions: Chills, influenza-like symptoms, injection site reaction, and local swelling 

Who Should Not Get The Hepatitis A Vaccine? 

The CDC recommends that anyone who meets the following criteria should not get the HAV: 

• Persons who have had a severe allergic reaction (e.g., anaphylaxis) after a previous dose of the HAV vaccine or have a severe allergy to an HAV vaccine component should not receive the HAV vaccine (8). 

Note: According to the CDC, anyone who is moderately or severely ill when the shot is scheduled should wait to get an HAV. At Dr. Green Mom, we recommend rescheduling even for mild illnesses when the risk for Hepatitis A is low and rescheduling is feasible.  

The Hepatitis A Vaccine and The Bottom Line 

Before the introduction of the Hepatitis A vaccine in 1996, the case-fatality rate for reported infections was approximately 0.3% across all ages, with a higher risk of death around 2% in adults over 40. 

To contract Hepatitis A, a person must ingest food or water contaminated with feces carrying the virus. Even if infected, the chance of death was relatively low at 0.3%, with about 100 deaths per year in the U.S. before vaccination. For perspective, 220,000 to 440,000 deaths occurred in 2013 due to medical malpractice—far exceeding deaths from Hepatitis A (not to minimize any loss of life, but to provide context). 

In the U.S., Hepatitis A is rare, and most children who contract the virus have no symptoms. However, the risk is higher when travelling to regions like Mexico or South America, where sanitation standards may differ. 

For those choosing to vaccinate, one dose of the Hepatitis A vaccine provides over 97% immunity (4), making it highly effective. When prioritizing vaccines, Hepatitis A is lower on the list, as the disease is typically mild in children. If vaccination is considered, waiting until age two may be an option. 

References 

1. Centers for Disease Control and Prevention. (n.d.). Hepatitis A – About hepatitis A. U.S. Department of Health & Human Services. Retrieved March 18, 2025, from https://www.cdc.gov/hepatitis-a/about/index.html 
2. Centers for Disease Control and Prevention. (2024). Hepatitis A. In CDC Yellow Book: Health information for international travel. U.S. Department of Health & Human Services. Retrieved from https://wwwnc.cdc.gov/travel/yellowbook/2024/infections-diseases/hepatitis-a 
3. Centers for Disease Control and Prevention. (2023). Hepatitis A vaccine: What you need to know [Vaccine Information Statement]. U.S. Department of Health & Human Services. Retrieved March 18, 2025, from https://www.cdc.gov/vaccines/hcp/current-vis/downloads/hep-a.pdf 
4. Centers for Disease Control and Prevention. (2023). Hepatitis A: Epidemiology and prevention of vaccine-preventable diseases (The Pink Book). U.S. Department of Health & Human Services. Retrieved March 18, 2025, from https://www.cdc.gov/pinkbook/hcp/table-of-contents/chapter-9-hepatitis-a.html 
5. Centers for Disease Control and Prevention. (n.d.). Hepatitis A – Clinical care. U.S. Department of Health & Human Services. Retrieved March 18, 2025, from https://www.cdc.gov/hepatitis-a/hcp/clinical-care/index.html 
6. Merck Sharp & Dohme LLC. (n.d.). VAQTA. Product insert from the vaccine manufacturer. https://www.fda.gov/media/74519/download?attachment. 
7. GlaxoSmithKline. (n.d.). HAVRIX. Product insert from the vaccine manufacturer. https://www.fda.gov/media/119388/download?attachment. 
8. Centers for Disease Control and Prevention. (n.d.). Who should not get vaccinated with these vaccines? U.S. Department of Health & Human Services. Retrieved March 18, 2025, from https://www.cdc.gov/vaccines/vpd/should-not-vacc.html 

Reviewed/Updated: 03/25
Content Created: 07/14