Hepatitis A vaccine - what you need to know

The hepatitis A vaccine helps protect you from hepatitis A, a viral infection that affects the liver. It is given as an injection into a muscle, usually in the upper arm. Young children may receive it in the thigh.

Most hepatitis A vaccines contain an inactive form of the virus. They cannot cause hepatitis A. A combination vaccine that protects against both hepatitis A and hepatitis B is also available for some people.

Protection is not immediate. Your immune system needs time to respond, and you may need more than one dose for long-term protection. The number and timing of doses are based on your age, the vaccine product, and whether you need protection quickly.

The vaccine prevents infection. It does not treat hepatitis A that has already developed.

Vaccination lowers your chance of becoming infected and spreading the virus to other people. Hepatitis A usually spreads when tiny amounts of infected stool enter the mouth, often through contaminated food, water, hands, or surfaces.

The vaccine is routinely offered during childhood in countries including the United States. It may also be recommended for an unvaccinated adult who wants protection.

You may have a particular reason to consider vaccination if you:

• Plan to visit a country where hepatitis A is common
• Have long-term liver disease or HIV
• Use recreational drugs
• Are a man who has sex with men
• Have an occupational risk of exposure to hepatitis A virus
• Are experiencing homelessness
• May have been exposed during an outbreak
• Have close contact with someone recently adopted from a country where hepatitis A is common

Vaccination may also be used after a known or likely exposure. It works best when given promptly. In some situations, immune globulin may be recommended as well as, or instead of, the vaccine. Immune globulin contains ready-made antibodies that provide temporary protection.

Many children and adults can safely receive a hepatitis A vaccine. Recommendations differ by country, age, previous vaccination, travel plans, health conditions, and exposure risk.

You should not receive another dose of the same vaccine if you had a severe allergic reaction, called anaphylaxis, after an earlier dose. You should also not receive a vaccine if you have a known severe allergy to one of its ingredients. The healthcare professional giving the injection can check the product’s ingredient list.

Vaccination may be delayed if you have a moderate or severe short-term illness, especially if you have a fever. A mild illness, such as a minor cold, does not usually require a delay.

Tell the vaccination team before the injection if you:

• Have had a serious reaction to any vaccine
• Feel faint around needles or have fainted after injections
• Have a bleeding disorder or take medicine that affects clotting
• Have a weakened immune system
• Are pregnant or breastfeeding
• Recently received immune globulin or another vaccine

Pregnancy and breastfeeding are not, by themselves, reasons to avoid an inactivated hepatitis A vaccine. Your healthcare team can consider your exposure risk and personal circumstances.

Infants below the approved age may need immune globulin rather than vaccination for short-term protection. Vaccine products also have different approved ages, so the available product may affect which vaccine you can receive.

Follow the treating facility’s own instructions first, because its procedures and the vaccine product it uses may differ.

You do not usually need to fast. Eat and drink normally unless the facility tells you otherwise. Having a drink and a light meal may help if you tend to feel faint with needles.

Bring your vaccination record if you have it. Also bring details of allergies, previous vaccine reactions, current medicines, and any recent possible exposure to hepatitis A.

Wear clothing that allows easy access to your upper arm. If needles make you anxious or you have fainted before, tell the person giving the vaccine. You may be able to receive it while sitting securely or lying down.

If the vaccine is for travel, arrange it as early as practical. Do not assume that a last-minute dose will provide full protection before departure. A travel health professional can assess whether you may also need immune globulin.

A healthcare professional will confirm your identity, review relevant health information, and check which vaccine and dose you need. You may be asked to confirm your consent.

The skin may be cleaned. A small needle is then used to inject the vaccine into a muscle, usually in the upper arm. The injection itself takes only a few seconds.

A small dressing may be placed over the site. You may be asked to remain nearby for about 15 minutes afterward. This allows the team to help if you feel faint or have an immediate allergic reaction.

You will be told whether another dose is needed and when it should be given. Keep the written or electronic vaccination record.

Your arm may feel sore, tender, or heavy for a day or two. A cool compress and gentle arm movement may help. Ask a pharmacist or healthcare professional about pain medicine if you need it.

You can eat and drink normally after vaccination. Drink fluids if you feel mildly feverish or tired.

Most people can return to normal activities the same day. Avoid strenuous use of the injected arm if it is uncomfortable, but complete rest is not required.

The vaccine itself does not create a routine driving restriction. You can drive when you feel well and can control the vehicle safely. Do not drive if you feel faint, dizzy, or unwell after the injection.

Most people can go back to work or school immediately. If you develop fever, tiredness, or a headache, you may prefer to rest until you feel better.

Common reactions are usually mild and short-lived. They can include pain, redness, or swelling where the injection was given. Some people develop a headache, tiredness, reduced appetite, nausea, or a mild fever.

Needles can cause fainting, particularly in teenagers and younger adults. Sitting or lying down for the injection and observation period can reduce the chance of injury from a fall.

A severe allergic reaction is uncommon but requires immediate treatment. Signs may include difficulty breathing, swelling of the face or throat, widespread hives, a rapid heartbeat, or sudden weakness.

Vaccines are monitored for safety after approval. A health problem occurring after vaccination is not always caused by the vaccine, but unexpected or serious events should be assessed and can be reported through your country’s vaccine safety system.

There is no immediate test result. Your immune system develops protection over the following weeks.

Complete every recommended dose for the best long-term protection. If you are late for a later dose, the series usually does not need to be restarted. Contact the vaccination provider to arrange the missed dose.

Routine blood testing to confirm immunity is not needed for most healthy people. Testing may be considered in selected situations, including certain immune system conditions or when proof of immunity is important.

The vaccine does not protect against hepatitis B, hepatitis C, or other causes of liver inflammation. A combination hepatitis A and B vaccine protects against those two viruses only.

You can reduce exposure by washing your hands with soap and water, using safe drinking water, and taking care with food hygiene. These steps are important, but they do not provide the reliable personal protection of vaccination.

Immune globulin can provide antibodies for short-term protection. It may be used when protection is needed quickly, when vaccination is unsuitable, or for certain people at higher risk after exposure. Its protection fades, so it is not a full substitute for long-term vaccination.

There is no stool test, blood test, or oral medicine that replaces vaccination. A blood test can show evidence of past infection or immunity, but it does not create protection.

Choosing not to be vaccinated avoids injection-related reactions but leaves you more vulnerable to hepatitis A. This matters especially during travel, outbreaks, or when liver disease could make an infection harder to manage.

Contact your healthcare team routinely if side effects are not improving after a few days, the injection-site redness or swelling continues to spread, or you are unsure when your next dose is due.

Ask promptly for advice if you were recently exposed to hepatitis A. Post-exposure treatment is time-sensitive and is most useful when arranged soon after contact.

Call emergency services for difficulty breathing, swelling of the face or throat, widespread hives, collapse, severe weakness, or other signs of a serious allergic reaction.

Seek urgent medical assessment for any severe or rapidly worsening symptom. Do not drive yourself if you feel faint or seriously unwell.

Will I be asleep?

No. Anaesthesia and sedation are not needed. You will be awake for the injection.

Can I drive home?

Usually, yes. Wait through the requested observation period and drive only if you feel well. Arrange another way home if you feel dizzy or faint.

How painful is it?

The needle may cause a brief sting. Arm soreness afterward is common but is usually manageable and short-lived.

When will I know it worked?

There is usually no test result. Protection develops over several weeks. Most healthy people do not need a blood test after completing the recommended doses.

How many doses will I need?

The schedule is based on your age and the vaccine product. Single-antigen hepatitis A vaccines and combined hepatitis A and B vaccines use different schedules.

What if I missed my next dose?

Arrange it when you can. A delayed series usually continues from where it stopped rather than starting again.