Twinrix Vaccine: How Many Doses of the Hepatitis A and Hepatitis B Vaccine?

Twinrix is a combined vaccine that brings protection against hepatitis A and hepatitis B together in one vaccine series. It can be considered for people who are not immune to either infection and who need protection. In this article I explain the differences between hepatitis A and hepatitis B, the Twinrix schedule and the points to consider before travel.

To answer “I had a jaundice vaccine before; do I need to be vaccinated again?”, you need to know which vaccine was given and how many doses. Although they are popularly called by the same name, hepatitis A and hepatitis B are different infections. Being immune to one does not mean you are protected against the other.

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What is hepatitis A?

Hepatitis A is a liver infection caused by the hepatitis A virus. The virus is mostly transmitted through contaminated food and drinks or through close contact.

Weakness, loss of appetite, nausea, abdominal pain, dark urine and yellowing of the eyes or skin may occur. In children it may pass without symptoms; in adults the illness may be more pronounced.

Hepatitis A does not become chronic. Even so, recovery can take weeks or months. In older people and those with existing liver disease, severe liver failure can rarely develop. For this reason, it should not be dismissed with the thought that “it will go away on its own anyway”. ^[1]

What is hepatitis B?

Hepatitis B is a viral infection that can be transmitted through blood and certain body fluids. Sexual contact, contact with infected blood and transmission from mother to baby during birth are important routes of transmission.

An important difference between hepatitis B and hepatitis A is that hepatitis B can become chronic in some people. Chronic infection can increase the risk of cirrhosis, liver failure and liver cancer over the years.

For this reason, protection against hepatitis B matters not only for preventing a short-term illness but also for long-term liver health. The vaccine does not treat an existing hepatitis B infection; it is used to prevent infection. ^[2]

What is the Twinrix vaccine?

Twinrix contains inactivated hepatitis A virus together with recombinant hepatitis B surface antigen. Because it contains no live virus, the components of the vaccine do not cause hepatitis A or hepatitis B.

The purpose of the combined vaccine is to bring the need for protection against two infections under a single programme. However, being combined does not automatically make it the best option for everyone.

If a person only needs to be vaccinated against hepatitis A or only against hepatitis B, a single vaccine may be preferred. ^[3]

Who should get the Twinrix vaccine?

Twinrix can be considered especially for people who are not immune to either infection and need protection against both.

Travel plans, occupation, household or sexual contact risks, previous vaccines and existing conditions are important in the assessment. For example, in a person at occupational risk for hepatitis B, it should also be determined whether hepatitis A protection is needed.

According to the European product information, Twinrix Adult is licensed for suitable individuals aged 16 and over. As products for children and age limits may differ between countries, the adult formulation should not be generalised to all ages. ^[4]

Is a blood test done before the Twinrix vaccine?

Rather than requesting the same test panel for everyone before vaccination, previous records and personal risks should be assessed. Where needed, tests help to identify a past infection or existing immunity.

In the assessment of hepatitis B, the HBsAg, anti-HBs and total anti-HBc tests provide different information. Looking only at the question “are there antibodies?” may not be enough to assess a current or past infection.

Especially in people whose vaccination history is unknown or who are at risk of hepatitis B, it is helpful to consider test results and the vaccination plan together. ^[2]

How many doses of Twinrix are given?

The standard Twinrix Adult vaccine series consists of three doses:

• First dose: On the chosen start date
• Second dose: One month after the first dose
• Third dose: Six months after the first dose

In the “month 0, 1 and 6” schedule, all dates are calculated from the first dose. It does not mean the third dose is given six months after the second.

The vaccine is given into the muscle. Planning the next appointments at the start of the series makes it easier to complete the doses on time. ^[4]

What is the accelerated Twinrix schedule?

For suitable adults who do not have enough time to complete the standard schedule, an accelerated schedule can be used. According to the European product information, doses are given on days 0, 7 and 21, followed by a fourth dose recommended at month 12.

This schedule aims to produce an immune response in a shorter time before travel. However, receiving the first three doses does not mean the month-12 dose is unimportant.

When the travel date is approaching, simply choosing a vaccine name is not enough. The destination country, length of stay and the person’s health status should be assessed together. ^[4]

How long does Twinrix protection last?

Long-term immunity is expected after a completed series. However, it is not appropriate to express the duration of protection as an exact number of years for everyone. The immune system, age and certain illnesses can affect the response to the vaccine.

The need for routine booster doses after a completed series in healthy people is not the same as follow-up in special situations such as dialysis or immunosuppression. In some groups, antibody assessment and additional doses may be needed. ^[5]

What are the side effects of the Twinrix vaccine?

Pain and redness at the injection site, headache and tiredness are among the most common side effects. Digestive complaints or a mild fever may also occur.

If a serious allergic reaction developed after a previous hepatitis A, hepatitis B or Twinrix dose, this should be shared before vaccination. Known allergies to vaccine components are also assessed separately. ^[5]

Frequently asked questions about the Twinrix vaccine