Skip directly to search Skip directly to A to Z list Skip directly to site content
CDC Home

Notice to Readers: FDA Approval for a Combined Hepatitis A and B Vaccine

On May 11, 2001, the Food and Drug Administration (FDA) licensed a combined hepatitis A and B vaccine (Twinrix®) for use in persons aged >18 years. Twinrix is manufactured and distributed by GlaxoSmithKline Biologicals (Rixensart, Belgium), and is made of the antigenic components used in Havrix and Engerix-B (GlaxoSmithKline). The antigenic components in Twinrix have been used routinely in separate single antigen vaccines in the United States since 1995 and 1989 as hepatitis A and B vaccines, respectively.

Vaccine Description

Each dose of Twinrix contains at least 720 enzyme-linked immunosorbent assays units of inactivated hepatitis A virus and 20 mcg of recombinant hepatitis B surface antigen (HBsAg) protein, with 0.45 mg of aluminum in the form of aluminum hydroxide and aluminum phosphate as adjuvants, 5.0 mg 2-phenoxyethanol as a preservative, and pH stabilizer in normal saline. Trace amounts of thimerosal (<1 µg mercury), neomycin (<20 ng), formalin (<0.1 mg), and yeast protein (<5%) also are present from the manufacturing process.

Indications and Usage

Twinrix is indicated for vaccination of persons aged >18 years against hepatitis A and B. Any person in this age group having an indication for both hepatitis A and B vaccination can be administered Twinrix, including patients with chronic liver disease, users of illicit injectable drugs, men who have sex with men, and persons with clotting factor disorders who receive therapeutic blood products (1,2). For international travel, hepatitis A vaccine is recommended for travelers to areas of high or intermediate hepatitis A endemicity; hepatitis B vaccine is recommended for travelers to areas of high or intermediate hepatitis B endemicity who plan to stay for >6 months and have frequent close contact with the local population (3). Primary vaccination consists of three doses, given on a 0-, 1-, and 6-month schedule, the same schedule as that used for single antigen hepatitis B vaccine.

Safety and Immunogenicity

Adverse experiences (AEs) were evaluated in clinical trials in which 6594 doses of Twinrix were administered to 2165 persons. Observed AEs generally were similar in type and frequency to those observed after vaccination with monovalent hepatitis A and B vaccines. The frequency of AEs did not increase with subsequent doses of Twinrix. No serious vaccine-related AEs were observed (GlaxoSmithKline Biologicals, unpublished data, 2001). Twinrix is contraindicated in persons with known hypersensitivity to any component of the vaccine.

Prelicensure clinical trials indicate that the immunogenicity of Twinrix is equivalent to that of the single antigen hepatitis vaccines. Data from 11 clinical trials that included adults aged 17--70 years indicated, 1 month after completion of the three dose series, seroconversion for antibodies against hepatitis A virus (anti-HAV titer >20 mIU/mL or 33mIU/mL [Enzymun-Test, Boehringer Mannheim Immunodiagnostics, Mannheim, Germany]) were elicited in 99.9% of vaccinees, and protective antibodies against HBsAg (anti-HBs >10 mIU/mL [AUSAB, Abbott Laboratories, Abbott Park, Illinois]) were elicited in 98.5% of vaccinees. One month after one dose of Twinrix, seroconversion to anti-HAV was seen in 93.8% of vaccinees and protective anti-HBs concentrations in 30.8%. One month after the second dose, seroconversion to anti-HAV was seen in 98.8% of vaccinees, and protective anti-HBs concentrations in 78.2%. The efficacy of Twinrix is expected to be comparable with existing single antigen hepatitis vaccines. The persistence of anti-HAV and anti-HBs following Twinrix administration is similar to that following single antigen hepatitis A and B vaccine administration at 4 years follow-up (GlaxoSmithKline Biologicals, unpublished data, 2001). Additional information is available from the manufacturer's package insert and GlaxoSmithKline Vaccines, telephone (800) 366-8900.


  1. CDC. Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 1999;48(no. RR-12).
  2. CDC. Hepatitis B virus: a comprehensive strategy for eliminating transmission in the United States through universal childhood vaccination: recommendations of the Immunization Practices Advisory Committee (ACIP). MMWR 1991;40(no. RR-13).
  3. CDC. Health information for international travel 2001--2002. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, CDC, 2001.

Use of trade names and commercial sources is for identification only and does not imply endorsement by the U.S. Department of Health and Human Services.

References to non-CDC sites on the Internet are provided as a service to MMWR readers and do not constitute or imply endorsement of these organizations or their programs by CDC or the U.S. Department of Health and Human Services. CDC is not responsible for the content of pages found at these sites. URL addresses listed in MMWR were current as of the date of publication.

All MMWR HTML versions of articles are electronic conversions from typeset documents. This conversion might result in character translation or format errors in the HTML version. Users are referred to the electronic PDF version ( and/or the original MMWR paper copy for printable versions of official text, figures, and tables. An original paper copy of this issue can be obtained from the Superintendent of Documents, U.S. Government Printing Office (GPO), Washington, DC 20402-9371; telephone: (202) 512-1800. Contact GPO for current prices.

**Questions or messages regarding errors in formatting should be addressed to The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
A-Z Index
  1. A
  2. B
  3. C
  4. D
  5. E
  6. F
  7. G
  8. H
  9. I
  10. J
  11. K
  12. L
  13. M
  14. N
  15. O
  16. P
  17. Q
  18. R
  19. S
  20. T
  21. U
  22. V
  23. W
  24. X
  25. Y
  26. Z
  27. #