Hepatitis A

What

Hepatitis A is an acute viral infection of the liver, which can cause mild to severe illness. The illness is usually self-limiting and needs no treatment. It is transmitted primarily by the faecal–oral route by ingesting contaminated food and water, or by direct contact with an infectious person. Hepatitis A is highly contagious.

Who

Hepatitis A vaccination is recommended for:

• Aboriginal and Torres Strait Islander children living in the Northern Territory, Queensland, South Australia and Western Australia
• people with medical risk factors, including chronic liver disease and developmental disabilities
• people whose occupation increases their risk of acquiring hepatitis A, including
  • people who live or work in rural and remote Aboriginal and Torres Strait Islander communities in the Northern Territory, Queensland, South Australia and Western Australia
  • people who regularly provide care for Aboriginal and Torres Strait Islander children in the Northern Territory, Queensland, South Australia and Western Australia
  • early childhood educators and carers
  • carers of people with developmental disabilities
  • plumbers and sewage workers
• people aged ≥1 year who travel to hepatitis A–endemic areas
• people whose lifestyle increases their risk of acquiring hepatitis A, including
  • people who have anal intercourse (including men who have sex with men, and sex industry workers)
  • people who inject drugs
  • inmates of correctional facilities

How

Hepatitis A vaccination is recommended for Aboriginal and Torres Strait Islander children living in hepatitis A–endemic areas in a 2-dose schedule at 18 months and 4 years of age.

Hepatitis A vaccination is recommended for all other risk groups (medical, occupational, travel, lifestyle) in a 2-dose schedule, with a minimum interval of 6 months between doses.

Why

Hepatitis A virus survives well in the environment outside its human host. Hepatitis A occurs worldwide. In Australia, before the introduction of the NIP funded Hepatitis A vaccination program in children, it was particularly prevalent in Aboriginal and Torres Strait Islander communities. The prevalence of Hepatitis A disease has decreased significantly since the implementation of the Hepatitis A vaccination program.

Hepatitis A vaccines available in Australia

The Therapeutic Goods Administration website provides product information for each vaccine.

See also Vaccine information and Variations from product information for more details.

Dose and route

Inactivated hepatitis A vaccines are given by intramuscular injection.

Recommended doses and schedules are shown in:

• Table. Recommended doses and schedules for monovalent hepatitis A vaccines
• Table. Recommended doses and schedules for combination hepatitis A and hepatitis B vaccines

For more details on combination hepatitis A/hepatitis B vaccines and schedules, see Hepatitis B.

Co-administration with other vaccines

Hepatitis A vaccines are inactivated vaccines.

Travellers can receive hepatitis A vaccines in Australia at any time before or after, or with, all other vaccines relevant to international travel⁹ and vaccines on the National Immunisation Program schedule.

If a combination hepatitis A/hepatitis B vaccine is not available, the person can receive both monovalent vaccines at the same time. Use separate syringes and administer at separate sites. See Interchangeability of hepatitis A vaccines and review the recommended minimum intervals.

Interchangeability of hepatitis A vaccines

Vaccine manufacturers use slightly different methods to produce the vaccines and quantify the hepatitis A virus antigen content. All monovalent hepatitis A vaccines that are given as a 2-dose course are interchangeable. See Table. Recommended doses and schedules for monovalent hepatitis A vaccines.

Schedules that mix combination hepatitis A/hepatitis B vaccines with monovalent vaccines are not routinely recommended.

An adult dose of Twinrix 720/20 (1.0 ml) contains half the hepatitis A antigen content of an adult dose (1.0 ml) of Havrix adult vaccine. These vaccines are therefore not interchangeable.

Contraindications

The only absolute contraindications to hepatitis A vaccines are:

• anaphylaxis after a previous dose of any hepatitis A vaccine
• anaphylaxis after any component of a hepatitis A vaccine

Combination hepatitis A/hepatitis B vaccines are contraindicated in people with a history of anaphylaxis to yeast.

Precautions

Women who are pregnant or breastfeeding

Hepatitis A vaccines are not routinely recommended for pregnant or breastfeeding women. However, these women can receive  these vaccines if necessary.

See Vaccination for women who are planning pregnancy, pregnant or breastfeeding and Table. Vaccines that are not routinely recommended in pregnancy: inactivated viral vaccines for more details.

People with latex allergy

The product information for both Vaqta paediatric/adolescent formulation and adult formulation states that the vial stopper, syringe plunger stopper and tip cap of the syringe contain latex. Consider the use of an alternative product in people with an allergy or sensitivity to latex.

The most common adverse events after receiving a hepatitis A vaccine are mild injection site reactions of short duration.

In both adults and children, systemic adverse events such as headache and fever are much less common than local adverse events.³

Injection site pain is reported in up to 60% of adults. About 15% of adults report headache, and about 5% report malaise or fatigue after vaccination.³ Up to 20% of children who receive hepatitis A vaccine report injection site pain.

Hepatitis A vaccines do not affect liver enzyme levels.

People with HIV can safely receive hepatitis A vaccines. The vaccines do not adversely affect the HIV viral load or CD4⁺ cell count.¹⁰

Hepatitis A is an acute infection of the liver. It is caused by hepatitis A virus (HAV). HAV is a picornavirus (a small single-stranded RNA virus).⁷

Pathogenesis

The incubation period is 15–50 days, with a mean of about 28 days.² Infected people excrete HAV in faeces for:

• up to 2 weeks before the onset of illness
• at least 1 week after the illness⁷

HAV does not cause chronic infection. Immunity after infection is lifelong.²

Transmission

Hepatitis A is a human infection. There is no animal reservoir.⁷ HAV is mainly transmitted by the faecal–oral route, primarily by ingesting contaminated food or water. The infecting dose is unknown, but is probably low.

HAV survives well in the environment outside the human host. It persists on hands for several hours and in food kept at room temperature for much longer. It is also relatively resistant to heat and freezing.

Laboratory diagnosis

Hepatitis A is diagnosed by detecting IgM antibodies against  HAV in serum during the acute illness.

Anti-HAV IgM is always present by the time the person presents with symptoms. IgM persists for 3–6 months after the acute illness.⁷

Serum anti-HAV IgG alone indicates past infection (or possibly immunisation) and therefore immunity.⁷

Symptoms of hepatitis A

In young children, hepatitis A virus usually causes either:

• asymptomatic infection, or
• very mild illness without jaundice

In adults, more than 70% of infected people have symptomatic infection. ²

Patients with symptomatic illness typically have a 4–10-day prodrome of systemic and gastrointestinal symptoms, including:

• fever
• malaise
• weakness
• anorexia
• nausea
• vomiting
• abdominal pain
• joint aches and pains
• yellow skin and eyes.

Dark urine is usually the 1st specific manifestation of acute hepatitis A infection. After 1–2 more days, the symptoms include jaundice and pale faeces.² Prodromal symptoms tend to wane when jaundice starts, but anorexia and malaise may persist. Pruritus and localised hepatic discomfort or pain may follow.⁷

The duration of illness varies. Most people feel better and have normal, or near normal, liver function tests within 1–2 months from the onset of illness.²

Complications of hepatitis A

Complications of hepatitis A are uncommon. Rarely, it may develop into fulminant hepatitis, for which mortality can be as high as 60%. ^2,11 The case-fatality rate of hepatitis A increases with age and varies according to the population.²

Hepatitis A does not cause chronic liver disease. Relapse occurs in up to 10% of cases, but all relapsed cases recover.

Hepatitis A in Australia

In recent years, hepatitis A notifications and hospitalisations have been low and trending down.¹ An increasing proportion of cases relate to travel to countries where hepatitis A is endemic.^12-14

Hepatitis A in Aboriginal and Torres Strait Islander children

The hepatitis A vaccination program was initially established in north Queensland in 1999 for Aboriginal and Torres Strait Islander children aged 18 months.¹⁵ In 2005, it expanded to include all Aboriginal and Torres Strait Islander children aged ≤2 years in:

• the Northern Territory
• Queensland
• South Australia
• Western Australia

Before the vaccination program, rates of hepatitis A in Aboriginal and Torres Strait Islander communities were very high. Factors associated with high rates were poor living conditions, overcrowding and poor sanitation.¹⁶ The hepatitis A vaccination program for Aboriginal and Torres Strait Islander children in endemic areas substantially reduced hospitalisations and notifications for this population.¹⁷

Many Aboriginal and Torres Strait Islander children >2 years of age in states and territories targeted by the hepatitis A vaccination program have received hep A vaccine. However, Aboriginal and Torres Strait Islander children remain at greater risk than non-Indigenous children of acquiring hepatitis A.¹⁷

See also Vaccination for Aboriginal and Torres Strait Islander people.

History of hepatitis A in Australia

Hepatitis A was a considerable public health problem in Australia in the 1990s. During this time, numerous outbreaks occurred in:

• childcare centres and preschools¹⁸
• Aboriginal and Torres Strait Islander communities¹⁵
• communities of men who have sex with men¹⁹
• schools and residential facilities for people with disability²⁰
• communities of people who inject drugs¹⁹

More recently, Hepatitis A outbreaks have been associated with a common food source.^17,21,22

Hepatitis A in other countries

Hepatitis A occurs worldwide. Developing countries with poor hygiene measures are at higher risk of hepatitis A infection and transmission.

In areas of high endemicity, such as parts of Africa, Asia, Central America and South America, up to 90% of children have been infected with hepatitis A.²

Hepatitis A is commonly reported in foodborne outbreaks.

Inactivated hepatitis A vaccines are prepared from hepatitis A virus (HAV) harvested from human diploid cell cultures.

Different strains of HAV are in different vaccines, but there is only 1 known serotype. Immunity induced by a particular strain probably protects against all strains. ⁷

Immunogenicity of hepatitis A vaccines

Hepatitis A vaccines are highly immunogenic in both children and adults. Seroconversion is nearly universal 4 weeks after vaccination.^7,23,24

Several studies have shown no significant difference in immunogenicity when comparing standard (6-12 months) and extended (20-31 months) dose intervals.^25-27

Efficacy of hepatitis A vaccines

Randomised controlled trials show that the vaccines have protective efficacy of nearly 100%.^28,29 This is supported by the apparent eradication of hepatitis A from Aboriginal and Torres Strait Islander communities in north Queensland and the Northern Territory since the vaccination program started in these regions.^15,17,30

A single dose of Hepatitis A vaccine can confer protection for several years. There is evidence to suggest that a single dose of  HAV hepatitis A vaccine can be 100% efficacious in preventing hepatitis A infection in seronegative young children in the study period from 6 weeks to 15 months post vaccination.³¹ Other studies have demonstrated effectiveness of a single dose in preventing hepatitis A infection up to 7 years after vaccination.^25,32

Duration of immunity

The duration of immunity after vaccination is uncertain. However, vaccine-induced antibodies against  HAV probably persist for many years. Booster doses are not required.³³

Transport according to National Vaccine Storage Guidelines: Strive for 5.³⁴ Store at +2°C to +8°C. Do not freeze.

Hepatitis A is a notifiable disease in all states and territories in Australia. Hepatitis A National Guidelines for Public Health Units has details about managing hepatitis A cases and contacts.³⁵

State and territory public health authorities can provide further advice about hepatitis A case management.

Post-exposure prophylaxis using hepatitis A vaccine or normal human immunoglobulin (NHIG) can prevent secondary cases in close contacts of hepatitis A cases. Refer to the most recent version of the Hepatitis A National Guidelines for Public Health Units for recommendations regarding the use of hepatitis A vaccine or NHIG for post-exposure prophylaxis for these close contacts, which vary according to the age or presence of medical conditions of the contact.

Normal human immunoglobulin

NHIG is a sterile solution of immunoglobulin, mainly IgG. It contains antibodies that are commonly present in adult human blood.

In Australia, the Australian Red Cross Blood Service supplies NHIG as a 16% solution.

Administration

Give NHIG by deep intramuscular injection, using an appropriately sized needle. Introduce NHIG slowly into the muscle, to reduce pain.

Never administer NHIG intravenously because of possible severe adverse events. To ensure that the needle is not in a small vessel, try to draw back on the syringe after intramuscular insertion.

A special product for intravenous use — called NHIG (intravenous) — is for people who need large doses of immunoglobulin.

For more details about the use of intravenous immunoglobulins, see Criteria for the Clinical Use of Intravenous Immunoglobulin in Australia.³⁶

Recommendations for using NHIG following possible Hepatitis A exposure

Use NHIG in close contacts of hepatitis A cases:​​​​³⁵

• when hepatitis A vaccine is contraindicated
• in infants <12 months of age
• in people who are immunocompromised and who might not mount a sufficient immune response after vaccination
• as an alternative option to hepatitis A vaccine for close contacts of hepatitis A cases who are aged >40 years – refer to the Hepatitis A National Guidelines for Public Health Units for further information and guidance on selection

NHIG in Australia provided by the Australian Red Cross Blood Service (ARCBS) contains enough antibody against hepatitis A virus to prevent infection or reduce disease severity if received within 2 weeks of exposure.³⁵

Routine vaccination in children

Havrix Junior

The product information for Havrix Junior vaccine states that when given in a two dose schedule, the second dose of the vaccine should be given 6 to 12 months after the first dose.

The Australian Technical Advisory Group on Immunisation (ATAGI) recommends that the second dose of Havrix Junior may be given anytime between 6 to 36 months after the first dose.

Vaqta Paediatric/Adolescent

The product information for the Vaqta Paediatric/Adolescent vaccine states that when given in a two dose schedule, the second dose of the vaccine should be given 6 to 18 months after the first dose.

The Australian Technical Advisory Group on Immunisation (ATAGI) recommends that the second dose of Vaqta Paediatric/Adolescent may be given anytime between 6 to 36 months after the first dose.

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