Hepatitis A (HepA) Vaccination

What is the hepatitis A (HepA) vaccine?

The hepatitis A (HepA) vaccine is used to prevent infection caused by the hepatitis A virus, which causes inflammation of the liver. It is found in the stools of an infected person and passed through contaminated food or water, especially food that is not cooked well, and through poor sanitation or hygiene practices by people who handle food. It can also be passed through close contact with an infected person.

In Singapore, most cases are caused by the consumption of raw or partially cooked shellfish like cockles.

A person is usually infectious for 2 – 3 weeks before they experience symptoms and during the first week of feeling unwell. Most people recover within 2 months with rest and medication to help relieve symptoms. However, there is no specific treatment for hepatitis A, with vaccination being the best prevention method.

How the hepatitis A (HepA) vaccine works

The hepatitis A vaccine uses an inactivated hepatitis A virus to stimulate an immune response. Your body then creates antibodies that will protect you from infection if you are exposed to the virus in the future.

Types of hepatitis A (HepA) vaccines

The hepatitis A vaccine can be given on its own or as a combination vaccine to protect against hepatitis A and B.

Hepatitis A vaccine. This is given in 2 shots, with the second one given 6 – 12 months later. Both shots are needed to provide long-term protection against hepatitis A, which lasts 10 – 20 years. It can be given to anyone aged 12 months and older.
Combination hepatitis A and B vaccine. This protects people against both hepatitis A and hepatitis B. It is taken in 3 doses over 6 months. All 3 shots are needed for long-term protection for both hepatitis A and hepatitis B. It can be given to anyone 18 years and older.

Why do you need the hepatitis A (HepA) vaccine?

The hepatitis A vaccine is recommended for those who live in or are planning to visit a country where hepatitis A is common.

Others who should consider taking the hepatitis A vaccine include:

Daycare staff
Food service workers
Healthcare workers
Sewerage and/or sanitation workers
Those with chronic liver disease, such as carriers of chronic hepatitis B
Those who work in labs that handle the hepatitis A virus or with primates infected with hepatitis A

When do you need the hepatitis A (HepA) vaccine?

The hepatitis A vaccine should be given before any potential exposure or up to 2 weeks after exposure to the hepatitis A virus. Protection begins 4 weeks after vaccination, but for optimum protection, this should be followed by a booster 6 – 12 months later.

Who should not receive the hepatitis A (HepA) vaccine?

While the hepatitis A vaccine is generally safe and effective, there are certain groups of people who should not receive the vaccine or should consult with their healthcare provider before getting vaccinated. These groups may include:

People with a severe allergic reaction (Anaphylaxis). Individuals who have had a severe allergic reaction to a previous dose of the hepatitis A vaccine or to any component of the vaccine should not receive it.
People with a previous severe allergic reaction to a vaccine component. If someone has had a severe allergic reaction to a component of the hepatitis A vaccine (such as neomycin), they should avoid the vaccine.
Pregnant women (in certain situations). While there is limited evidence suggesting that the hepatitis A vaccine is safe during pregnancy, it is generally recommended to delay vaccination until after pregnancy unless the risk of hepatitis A infection is high.
People with a moderate to severe illness. Individuals with a moderate to severe illness, especially those with a fever, may be advised to wait until they recover before receiving the vaccine. However, a mild illness is not usually a reason to postpone vaccination.
Individuals with a weakened immune system. People with weakened immune systems due to conditions such as HIV/AIDS or immunosuppressive medications may not respond as effectively to the vaccine. However, in some cases, vaccination may still be recommended. It is important to consult with a healthcare provider in these situations.
Infants younger than 1 year old. The hepatitis A vaccine is typically not given to infants younger than 1 year old. However, they may receive the vaccine at 6 – 11 months of age in certain high-risk situations or before international travel.

How do you prepare for the hepatitis A (HepA) vaccine?

Before you take the vaccine, you should inform your doctor of the following:

Any existing medical conditions, especially those related to bleeding disorders, cancer and conditions affecting your immune system
Any medication you are taking
If you are allergic to any of the ingredients found in the vaccine
If you are feeling unwell
If you are pregnant or breastfeeding

What can you expect when getting the hepatitis A (HepA) vaccine?

The hepatitis A vaccine is typically injected into the deltoid muscle in your upper arm. You may feel a slight pinch or stinging sensation during the injection and may be asked to wait for a short period (15 – 30 minutes) after the injection to ensure there are no immediate allergic reactions.

The hepatitis A vaccine requires 2 doses for complete protection. The second dose is usually given 6 – 12 months after the first dose.

What are the common side effects of the hepatitis A (HepA) vaccine?

It is common to experience some side effects. These usually go away on their own, or you may try to relieve them with home remedies or over-the-counter medication.

Common side effects include: