Hepatitis A Vaccine and Hepatitis B Vaccine (Injection, Intramuscular)

As with other vaccinations, this vaccine contains a mild or non-infectious form of the virus, or viruses, in this case, introduced to the body in the form of antigens. It causes the body to produce antibodies that serve as protection against the disease in case of an attack in future. The effect can last for one's entire lifetime. It is a preventive rather than curative means of therapy.


The hepatitis A- hepatitis B combination vaccine is also commonly known by its brand name, Twinrix. In countries like Canada, it exists in two forms under the same brand; Twinrix Junior for children and Twinrix Adult for grown-ups. The vaccine is given as a preventive measure against viral infections of two types of the hepatitis viruses; A and B.

Hepatitis A disease occurs when the body is infected with the virus after which it is named (Hepatitis A virus or HAV). Infection occurs through contaminated water or food. It may also spread through close personal contact with an already infected individual. For instance, one may contract the virus if they live in the same house with an infected person. The level of sanitation affects disease frequency. Therefore, the virus and its spread will occur at a higher rate in places where there are low levels of hygiene or poor sanitary conditions. Different nations have varied levels of sanitation with some lacking proper water and waste management systems. For this reason, it is vital that one traveling to other countries especially where proper sanitation systems are not in place, receive the Hepatitis A vaccine. HAV causes a severe liver disease that leads to multiple complications which may eventually result in the death of the diseased person.

The hepatitis B virus or HBV, on the other hand, causes hepatitis B disease. Spread, and infection occurs by a more intimate contact than hepatitis A. It involves exchange of or contact with an infected person's body fluids for example saliva, blood, vaginal fluid or semen. Some channels through which this is made possible include sexual transmission, from a mother to a child, through sharing of sharps like needles and blades.

The bivalent vaccine contains constituents found in the hepatitis A vaccine (Havrix) and the hepatitis B vaccine (Engerix). Inactive antigens of the hepatitis A disease virus and non-infectious hepatitis B antigens are also component products in the vaccine.Injection and exposure of the body to these mild forms of the viruses in Twinrix triggers the production of antibodies against HAV and HBV. The fact that the virus in the vaccine is inactive and the presence of other components ensures that it does not cause the diseases. The antibodies formed upon immunization remain in the body so that when natural exposure to either virus occurs, they trigger an immune response whereby these antibodies recognize and attack the viruses thus preventing the diseases.

Twinrix is not a routine immunization. It is usually recommended for particular groups of people or individuals who are at high risk of infection from their work and certain behaviors or if particular conditions are at play. Examples of these persons are:

  • Healthcare professionals who handle or frequently come into direct contact with body fluids such as blood in their work
  • People working directly with these viruses in laboratories
  • People in the military and the police
  • Emergency medical service providers such as first-aiders and paramedics
  • People in waste management, especially those who handle sewage
  • Individuals who are working or committed in institutions such as prisons and correctional facilities, children day-care centers and rehabilitation or alcohol and drug treatment centers, homes for the aged and centers for those with mental impairment or severe learning difficulties.
  • Other at-risk individuals include those traveling to high-risk areas. There are specific parts of the world where it is essential to have received the Twinrix shot before traveling. Among the most common are:
  •  Eastern and Southern Europe
  •  South and South East Asia Africa
  •  The Middle Eastern regions
  •  South America and Central America (Mexico)
  •  The former Soviet Union
  •  The Caribbean islands
  • Those relocating to or already living in these and other high-risk areas (that is, those where HAV has a high frequency of occurrence and at high risk of contracting HBV).
  • Those living with or in close contact with infected persons
  • People involved in behavior such as drug abuse by injection
  • Those who engage in risky sexual activity such as homosexuals, bisexuals, people with multiple sex partners or t High-risk individuals due to conditions such as hemophilia (or those who regularly receive blood products) are also at a high risk
  • Those with chronic liver disease
  • Patients undergoing hemodialysis and the staff in these units

The recommendation does not limit the reception of the vaccine to the above individuals only.

Condition It Treats

It helps prevent:

  • Viral infection by hepatitis A virus in adults and children (1 year and above)
  • Viral infection by hepatitis B virus in adults and children above one year

Type Of Medicine

  • Accine

Side Effects

Besides the desired effects of the hepatitis A and hepatitis B recombinant vaccine, other effects may present. Some of these undesirable side effect appearing alongside the needed results may be so serious that they require medical attention while others disappear with time and as the patient adjusts to the drugs. They also appear in different frequencies with some being more common than others.

Among the more common undesired effects accompanying Twinrix include:

  • Fever reaching temperatures of over 99.5 degrees Fahrenheit
  • Congestion in the ears and nose
  • Sneezing and runny nose
  • General body weakness and unusual fatigue
  • Body aches
  • Loss of voice
  • Pain and inflammation (soreness, tenderness, and redness) at the site of injection

Other side effects that are rare and others whose incidence is unknown may also present. These include characteristic symptoms of the allergic reaction such as hives, swollen face, eyes, nasal area and neck, chest tightness and wheezing, difficulty in breathing and swallowing and itchiness of the skin. One may also experience abdominal pain, light-headedness, and restlessness, headaches, joint and muscle pain or stiffness, dry mouth, hyperventilation, either unusual drowsiness or sleeplessness and a racing heartbeat. These are less frequent but may still occur.

Side effects whose incidence is unknown include bleeding gums, dark, tarry and bloody stool and well as blood in urine and bladder control issues. Others are confusion, agitation, irritability and forgetfulness, heavy menstruation, nausea, slight paralysis or numb extremities, sores and blisters on skin and mouth area, jaundice, heartburn and indigestion among others.

Not all side effects mentioned will appear. There are also those which are not mentioned in the list above. However, it is prudent to seek medical advice for any worrying and (even mild) side effects.


Twinrix vaccine should only be given by a qualified medical practitioner or under the supervision of one. The dosage form in which this product is available is a suspension. It is delivered via injection into the muscles (the intramuscular route).

The one administering the vaccine should ensure they use a properly stored, non-expired formulation. The suspension exists in a 1ml single-dose injection vial or a pre-filled syringe for each dose for individuals above the age of 18. For Twinrix junior, the product is in 0.5 ml doses. Ensure to check if the seal is broken. During storage, the suspension may settle and separate into a colorless fluid with a white deposit at the bottom. Re-suspend the vaccine before use for example by shaking the vial or tipping the syringe upside down and back up repeatedly for 15 seconds or so. You want to see that the liquid forms a homogenous cloudy white appearance upon inspection. Once it appears so, it is ready for use. Check to see that it has no discoloration. When using a vial, withdraw a 1ml dose using sterile needle and syringe and inject intramuscularly. Avoid changing needles unless necessary (for instance, if contamination or damage occurs). If you are using a pre-filled syringe, attach a sterilized needle and deliver the shot via the IM route. Administration in the upper arm region is recommended for maximum effectiveness in adults and adolescents. In children, it is typically given in the thigh area.

One receives this vaccine in three doses. You get the first shot. Then a period of one month after the first treatment, you receive the second dose. The third one comes six months after the very first dose. This procedure is standard and should be followed unless your healthcare practitioner tells you otherwise. Normally, the doctor schedules these dates for example on an appointment card and the recipient just has to show up to receive the shots. Getting the doses at the right time is of extreme importance. If you skip a dose or a miss scheduled injection, inform your doctor right away to reschedule.

Besides the standard procedure, there is an alternative fast-tracked dosing procedure whereby the doctor administers a series of four doses instead of the usual three. Each treatment is also 1 ml. However, in this accelerated dose administration, one receives the second dose seven days after the initial shot. Then the next one is given on the 21st day and the fourth on the 30th day so that one receives all the doses in one month (30 days) instead of the usual six months. An additional booster shot is given in the twelfth month. This last jab is not a fundamental requirement for everyone but may be necessary for those with weak immunity.

Major Drug Interactions

Using different drugs same time may bring about an effect on the body as they interact or change each other's efficacy. These results come about because some medication, when taken concurrently will interact with each other. It is prudent for a patient to inform the doctor of all medicine that they are taking at the time of administration, let them know of a recently completed dose or tell them about a medication regimen that they are usually on whether prescription or non-prescription. Certain types of food including tobacco and alcohol may also affect drug efficiency, and the doctor should discuss with the patient on the issue. There may also be contraindications in case of the presence of another health problem.

Twinrix should not be administered to individuals with a yeast allergy. Also, if you are allergic to neomycin, use of this vaccine is not advisable. If a patient is sick with a moderate to severe ailment accompanied by fever, it may be best to give the vaccination at a later time. Note that you should not mix this vaccine with any other vaccine or medication in the same syringe or vial.


Every vaccine or drug is administered only if the benefits outweigh the health risks and for a non-routine vaccination such as this, one has to seek professional medical advice before use because certain conditions will qualify or disqualify its use. Of paramount importance is to inform your doctor if you have ever had or are having an unusual hypersensitivity reaction to the product. It is also crucial that you let them know if you experience allergic reactions to any other medicines because they may have similar components or produce a similar effect as Twinrix. Doctors should carefully review the patient's immunization and medical history. And one should inform the clinician of allergic reactions to other products besides medicine such as food, animals, and preservatives among others as well.

Note that even though the hepatitis A- hepatitis B recombinant vaccine can prevent the respective infections across all ages, there are precautions for use in various populations. Extensive clinical studies on the effects of the vaccine to age are yet to be established. Conclusive reports on efficacy and safety in pediatric (i.e., under 18) and geriatric (over 65) use of the vaccine are lacking. However, so far there is not much incidence of age-specific problems. For pregnant women and lactating mothers, there is also insufficient research in both animal and human clinical studies on how it may affect the mother and the fetus or infant. However, its use in pregnancy or during breastfeeding is warranted if the benefits are more than the risks involved.

Additional precautions to consider include the fact that rubber latex used on the caps of pre-filled syringes may cause hypersensitivity reactions. Also, fainting is associated with the administration of injectable vaccines.


Store the vial or prefilled syringe in a cool and dry place. It should be away from direct heat, moisture and direct light at room temperature.


Acquired immunity from vaccination is an integral part of modern medicine and has helped prevent and even eradicate some of the most devastating illnesses once existent. The hepatitis A and hepatitis B combined vaccine is an essential non-routine vaccination especially for at-risk individuals such as are mentioned above. The viruses cause serious liver diseases including hepatocellular carcinoma (cancer of the liver), liver cirrhosis, viral hepatitis and chronic liver disease and its subsequent complications. The vaccination can provide immunity for the individual for at least a decade for hepatitis A and five years for hepatitis A but may even last for their entire lifetime.

Note that it this product is specified for active immunization against HAV and HBV. Therefore it only prevents diseases caused by the hepatitis A virus and the hepatitis B virus-caused infections (for all its known subtypes). However, it does not protect against other forms of hepatitis such as hepatitis E and hepatitis C. Another critical issue to take note of is that vaccines (including Twinrix) do not guarantee a hundred percent protection against the diseases they prevent nor do they protect all individuals. For the working of Twinrix vaccine, in particular, hepatitis A and B have relatively long periods of incubation which is a limit to the vaccine's effectiveness. Moreover, the vaccine will not prevent hepatitis infections which are not recognized at the time of immunization.

Other conditions of use that may affect the effectiveness of the drug include the dietary, medical and conditional contraindications. It is crucial for medical practitioners to understand a patient's medical history and allergies to advice on the treatment accordingly. Always inform your doctor of any drugs you are taking or any conditions you are predisposed to before starting a dose. Follow instructions, heed the warnings on the label and report all side effects to reap the wanted benefits of the hepatitis A and hepatitis B (recombinant) vaccine.