Twinrix is a vaccine against hepatitis A and hepatitis B, manufactured by GlaxoSmithKline. Twinrix is administered over three doses.
The name was created because it is a mixture of two earlier vaccines - Havrix, an inactivated-virus Hepatitis A vaccine, and ENGERIX-B, a recombinant Hepatitis B vaccine.
Twinrix first entered the market in early 1997.
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Twinrix can be administered on the same schedule as monovalent Hepatitis B vaccine: at 0- 1- and 6- months. In some circumstances, an accelerated dosing schedule of 0- 7- and 21-to 30- days followed by a booster at 12 months can be used and is believed to have similar efficacy as the traditional schedule.[1]
The CDC reports that clinical trials found the following levels of protection against Hep A and Hep B one month after each dose:[2]
GlaxoSmithKline claims that its studies found 70% of subjects had antibodies against hepatitis B a month after just the first dose, however.[3]
Although Twinrix has enjoyed much success and has provided benefit for millions, there is one report concerning a putative exacerbation of autoimmune hepatitis possibly due to innoculation by Twinrix.[4]. It must be noted, however, that since the vaccination for Hepatitis A is a killed vaccine, and Hepatitis B is a recombinant vaccine, that there is no possibility for the vaccination to mutate and cause Hepatitis A or B in an immunized individual.
In order to promote this new vaccine, GlaxoSmithKline launched a TV ad advertising, dramatizing that in Caribbean destinations like the Dominican Republic, a person can get Hepatitis A and/or Hepatitis B from an otherwise calm beach setting, from the sand soil up to the swimming water.[5]
TWINRIX, HAVRIX and ENGERIX-B are registered trademarks of GlaxoSmithKline; if the same vaccine is available from others, it will have another name.