What is Twinrix Adult?
Twinrix Adult is a vaccine available as a suspension for injection. It contains inactivated (that is killed) hepatitis A virus and parts of the hepatitis B virus as active ingredients. It is available in 1 ml ampoules and in 1 ml pre-filled syringes.
What is Twinrix Adult used for?
Twinrix Adult is used to protect against infection with hepatitis A and hepatitis B (diseases that affect the liver). The vaccine can be given to adults and adolescents aged 16 or over who are not already immune to these two diseases and who are at risk of contracting both.
The medicine can only be obtained with a prescription.
How is Twinrix Adult used?
The recommended vaccination protocol for Twinrix Adult consists of three doses, with an interval of one month between the first two doses and an interval of five months between the second and third doses. The vaccine is injected into the muscle of the upper arm.
The three injections can be given exceptionally over a three-week period for adults who need rapid protection before a trip. In these cases, a fourth injection is recommended 12 months after the first dose.
Those who are given the first dose must necessarily complete the entire protocol provided for Twinrix Adult. A booster dose of Twinrix Adult, or a different vaccine for hepatitis A or B, can be given according to official recommendations.
How does Twinrix Adult work?
Twinrix Adult is a vaccine. Vaccines act by "teaching" the immune system (the body's natural defenses) to defend itself against a disease. Twinrix Adult contains a tiny amount of inactivated hepatitis A virus and "surface antigen" (surface proteins) of the hepatitis B virus. When a person receives the vaccine, the immune system recognizes viruses and surface antigens as "strangers" and produces antibodies against them. If he comes into contact with the virus in the future his immune system will be able to produce antibodies more quickly. Antibodies help protect the body from diseases related to these viruses.
The vaccine is "adsorbed". This means that viruses and surface antigens are fixed on aluminum compounds to stimulate a better response. The surface antigens of the hepatitis B virus are produced by a method called "recombinant DNA technique", that is produced by a yeast that has received a gene (DNA) which makes it capable of producing proteins.
The active substances in Twinrix Adult have been available in the European Union (EU) for several years in separate vaccines: Havrix Adult for protection against hepatitis A and Engerix-B for protection against hepatitis B.
How has Twinrix Adult been studied?
Twinrix Adult has been studied in three main studies involving 843 healthy people between the ages of 18 and 60, most of them under the age of 40. Each person received doses of Twinrix Adult months 0, 1 and 6 of the protocol. The main measure of effectiveness was the percentage of people who had developed antibodies against hepatitis A and B.
Other studies have observed the persistence of antibodies both after vaccination in adults and adolescents and with the rapid protection protocol for adults in three weeks.
What benefit has Twinrix Adult shown during the studies?
Studies have shown that for hepatitis A, antibodies were detected in 94% of adults after the first dose, in 99.5% after the second dose and in 100% after the third dose. For hepatitis B, antibodies were detected in 71% of adults after the first dose, 97% after the second dose and 99.7% after the third dose.
Other studies have shown the presence of antibodies for up to five years. Also the vaccination protocol in three weeks led to the production of antibodies in about 83% of patients, reaching up to about 89% after the booster dose at month 12.
What is the risk associated with Twinrix Adult?
The most common side effects of Twinrix Adult (seen in more than 1 in 10 doses of the vaccine) are headache, pain and redness at the injection site, and exhaustion (tiredness). For the full list of all side effects reported with Twinrix Adult, see the Package Leaflet.
Twinrix Adult should not be used in people who may be hypersensitive (allergic) to any of the active ingredients, to any of the other ingredients, or to neomycin (an antibiotic). It must also not be used in people who have had an allergic reaction after receiving vaccines against hepatitis A or hepatitis B. The vaccination with Twinrix Adult must be postponed in patients with a sudden high fever. Twinrix Adult should never be injected into a vein.
Why has Twinrix Adult been approved?
The Committee for Medicinal Products for Human Use (CHMP) has determined that the benefits of Twinrix Adult are greater than its risks for use in non-immune adults and adolescents from the age of 16, who are at risk of being infected by either hepatitis A from hepatitis B. The committee recommended the release of marketing authorization for Twinrix Adult.
More information on Twinrix Adult:
On 20 September 1996 the European Commission issued a marketing authorization for Twinrix Adult, valid throughout the European Union, to GlaxoSmithKline Biologicals sa. The marketing authorization was renewed on 20 September 2001 and 20 September 2006.
The full EPAR for Twinrix Adult can be found here.
Last update of this summary: 02-2008.
