Everything You Need to Know About the Hepatitis A Vaccine

Introduction

Hepatitis A is a contagious liver infection caused by the hepatitis A virus (HAV), which primarily spreads through feco-oral route, and contaminated food, water or close contact with an infected person. It remains a significant public health concern, especially in areas with inadequate sanitation and limited access to clean water¹.  

Most people recover fully and develop a long-lasting immunity against the HAV once they have been affected. However, in rare cases, hepatitis A can lead to severe complications, including liver failure (more common in older adults with underlying conditions). Fortunately, a safe and effective vaccine is available that offers reliable protection against this preventable disease². In this article, we will discuss the hepatitis A vaccine for adults and children, its benefits, and why it’s important for public health. 

What is the Hepatitis A Vaccine?

The hepatitis A vaccine uses an inactivated HAV virus to safely stimulate the body’s immune system and provide long-term protection (possibly life long after two doses) against infection³. 

When a vaccine is given, the white blood cells (WBCs) that fight an infection recognise the vaccine’s antigen (specific virus protein) and trigger specific WBCs (B and T cells). The B  cells then multiply and create antibodies (proteins) and the T cells help in immune regulation and memory for protection against the virus when encountered in the future⁴.  

Bonus: The vaccine also contains aluminium that boosts the immune response by keeping the antigen at the injection site longer and stimulating immune cells to release signals that enhance protection⁴. 

Why is the Hepatitis A Vaccine Important?

The hepatitis A vaccine plays a crucial role in offering protection from the harmful effects of the HAV. Key hepatitis A vaccine uses include: 

• Protects against liver inflammation caused by the HAV⁴. 
• Trains the immune system to recognise the HAV and fight rapidly upon exposure³.
• Helps avoid severe illness and complications from hepatitis A (more common in older adults with liver diseases)¹. 
• Reduces the spread of the virus in communities, lowering outbreak risks⁴. 
• Contributes to overall public health by decreasing disease incidence³. 

Who Should Get the Hepatitis A Vaccine?

The hepatitis A vaccine is generally recommended for individuals at increased risk of infection or complications. The following groups of people are especially advised to get vaccinated against the HAV: 

• All children aged 1 year and older. 
• Travellers to countries or regions with a high prevalence of hepatitis A⁵. 
• People with chronic liver disease⁴. 
• Men who have sex with men (MSM). 
• People who use injection (or non-injection) drugs⁴. 
• Individuals experiencing homelessness⁵. 
• People with clotting factor disorders, such as haemophilia⁴. 
• Family members of individuals recently adopted from a place where hepatitis A is common⁵. 

Types of Hepatitis A Vaccines

There are several types of hepatitis A vaccines available in the market currently that provide effective protection against HAV. These include both single-antigen vaccines and combination vaccines⁶: 

1. Single-Antigen Hepatitis A Vaccines

These vaccines protect only against the HAV. These are approved for individuals aged 1 year and older and include: 

• Havrix® (manufactured by GlaxoSmithKline) 
• Vaqta® (manufactured by Merck & Co.) 

Only inactivated vaccines are in use currently; no live-attenuated Hep A vaccines are licensed in most countries, including the U.S. Both of these are also inactivated vaccines and require a two-dose schedule for long-term protection. 

2. Combination Vaccine

This vaccine (inactivated) protects against both hepatitis A and hepatitis B viruses. They are approved for use in individuals aged 18 years and older and include: 

• Twinrix® (manufactured by GlaxoSmithKline) 

It is important to note that this vaccine is not a replacement for single-antigen vaccines and used when protection against both Hepatitis A and B is needed.  

Since both vaccines are equally effective, your doctor can help determine the most suitable option based on age, health status, and risk of exposure. 

When and How Often to Get the Hepatitis A Shot

The hepatitis A vaccine for adults and children is typically given as part of a two-dose schedule for full protection. Here’s what you need to know about the hepatitis A vaccine dose schedule⁴. 

Single-antigen hepatitis A vaccines are given in two doses⁴: 

• The first dose is recommended at 1 year of age or older. 
• The second dose is usually given 6 to 18 months later. Please note that while this is the suggested time interval, there is no maximum limit and a delayed second dose does not require restarting the series. 

Combination hepatitis A vaccines are given in three doses: 

• The first dose is recommended at 18 years of age or older⁶. 
• The second dose is usually given after 1 month of the first dose. 
• The third dose is generally given 5 months after the second dose (6 months after the first dose)⁴. 
• In combination vaccines, an accelerated schedule (doses at 0, 7, and 21 to 30 days, followed by a booster at 12 months) can be used in certain situations, such as for travellers⁷.  

For optimal effectiveness of the vaccine, you should follow your doctor’s suggestion for the hepatitis A vaccine dose schedule. 

Note: The optimal hepatitis A vaccine age to start immunisation is 12 months, ensuring early protection during childhood. That being said, there is no upper limit for the hepatitis A vaccine age, and adults at risk can be vaccinated safely at any time. 

Also Read: Everything To Know About the Influenza Vaccine & Its Importance

How the Vaccine is Given

The hepatitis A vaccine is administered as an intramuscular injection, typically into the thigh for infants and toddlers (under 3 years) and into the upper arm for children aged 3 years and older and adults⁴.  

It is typically given at clinics, travel health centres, hospitals, or public health departments⁸. If you’re unsure about when or where to get vaccinated, consult your doctor for guidance and support. 

The vaccine has a well-established record of safety and effectiveness: 

• Over 95% of recipients develop protective immunity after the first dose⁹. 
• Full vaccination, after two doses, offers long-lasting immunity (up to 20 years)³. 

Possible Hepatitis A Vaccine Side Effects

This vaccine is generally well tolerated, with most hepatitis A vaccine symptoms being mild and short-lived. Some common but mild hepatitis A vaccine side effects include⁴: 

• Soreness or redness at the injection site 
• Mild fever 
• Fatigue or tiredness 
• Headache 
• Occasional rash 

These hepatitis A vaccine side effects typically get better on their own in a few days. 

Serious side effects such as anaphylaxis (difficulty breathing, swelling of the face or throat, or hives) may also occur, although extremely rare¹⁰. 

When to See a Doctor

While most people experience no or only mild hepatitis A vaccine after effects, you should seek medical attention if you notice: 

• Signs of a severe allergic reaction (anaphylaxis).  
• Persistent or worsening symptoms after vaccination. 
• Any unusual or severe health changes following the shot. 

If in doubt, always consult your doctor for reassurance and appropriate care regarding the hepatitis A vaccine’s effects. 

Conclusion

Hepatitis A vaccine plays a vital role in preventing acute hepatitis A, which can lead to severe liver problems, especially in older adults or those with pre-existing liver disease. This vaccination is especially important for young children, travellers to high-risk regions, MSM, IV drug abusers and individuals with chronic liver conditions. By getting vaccinated, you not only protect yourself but also help stop the spread of the virus in the community. 

The vaccine is safe, effective, and well-tolerated, providing long-term protection and helping lower the incidence of hepatitis A cases worldwide. The hepatitis A vaccine after effects are also usually mild and resolve within a few days without any treatment.  

So, if are not vaccinated or in the high-risk group , talk to your doctor about hepatitis A vaccination; it’s a simple and reliable step toward safeguarding your liver health!

Also Read: HPV Vaccine: What is It, When to Be Taken, Importance & Side Effects 

Frequently Asked Questions (FAQs)

References

1. Girish V, Grant LM, John S. Hepatitis A [Internet]. StatPearls Publishing; [cited 2025 Jun 4]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459290/ 
2. World Health Organization. Hepatitis A [Internet]. World Health Organization; [cited 2025 May 28]. Available from: https://www.who.int/news-room/fact-sheets/detail/hepatitis-a 
3. Zhang L. Hepatitis A vaccination. Hum Vaccin Immunother. 2020 Jul 2;16(7):1565-1573. Available from: https://pmc.ncbi.nlm.nih.gov/articles/pmid/32649265/ 
4. Bhandari P, Brett C, Batool A, et al. Hepatitis A Vaccine [Internet]. StatPearls Publishing; [updated 2023 Jun 21; cited 2025 Jun 4]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554604/ 
5. Centers for Disease Control and Prevention. Hepatitis A Vaccine Administration [Internet]. Centers for Disease Control and Prevention; [cited 2025 May 28]. Available from: https://www.cdc.gov/hepatitis-a/hcp/vaccine-administration/index.html 
6. Centers for Disease Control and Prevention. Hepatitis A Vaccine [Internet]. Centers for Disease Control and Prevention; [cited 2025 May 28]. Available from: https://www.cdc.gov/hepatitis-a/vaccination/index.html 
7. Mileno M, Lau C, Lonks J, Garland J, Sanchez M, Nau G, Larkin J. Vaccines for Adult Travelers. In: Keystone JS, Kozarsky PE, Freedman DO, Nothdurft HD, Connor BA, editors. Travel Medicine. 4th ed. Elsevier; 2019. Available from: https://www.researchgate.net/publication/330054961_Vaccines_for_Adult_Travelers 
8. Centers for Disease Control and Prevention. Travelers’ Health [Internet]. Centers for Disease Control and Prevention; [cited 2025 May 28]. Available from: https://wwwnc.cdc.gov/travel/page/travel-vaccines 
9. Herzog C, Van Herck K, Van Damme P. Hepatitis A vaccination and its immunological and epidemiological long-term effects – a review of the evidence. Hum Vaccin Immunother. 2021 May 4;17(5):1496-1519. Available from: https://pmc.ncbi.nlm.nih.gov/articles/PMC8078665/ 
10. Centers for Disease Control and Prevention. Possible Side Effects from Vaccines [Internet]. Centers for Disease Control and Prevention; [cited 2025 May 28]. Available from: https://www.cdc.gov/vaccines/basics/possible-side-effects.html 
11. Centers for Disease Control and Prevention. Guidelines for Vaccinating Pregnant Women [Internet]. Centers for Disease Control and Prevention; [cited 2025 May 28]. Available from: https://www.cdc.gov/vaccines-pregnancy/hcp/vaccination-guidelines/index.html

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