FDA Approves Tdap Booster Vaccine

The US Food and Drug Administration (FDA) has expanded the use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) absorbed vaccine (Adacel) to include repeat vaccinations for tetanus, diphtheria, and pertussis.

With the indication, the Sanofi Pasteur product becomes the first and only Tdap vaccine approved for repeated dose in people aged 10-64 years old, 8 years or more after their first vaccination, in the US. It is also currently the only Tdap vaccine available in syringe made without natural rubber latex, in the event of a patient allergy.

The FDA’s indication was based on an application that included clinical data showing the efficacy and safety of Adacel in adult patients. The trial, involving 1300-plus adults aged 18-64 years old, compared the vaccine to a tetanus-diptheria (Td) vaccine 8-12 years after a previous dose of Adacel. Trial results showed that a second dose of the investigative vaccine in adults administered 8-12 years after a previous dose was associated with no significant difference in adverse events compared to the Td vaccine group.

Among the 999 Tdap vaccine patients, 87.7% reported at least 1 injection-site reaction, compared to 88% of the Td vaccine recipients (n= 328).

Investigators, led by Scott A. Halperin, MD, a professor in the Division of Infectious Diseases, Dalhousie University, concluded the study results support booster doses of Tdap to maintain protection in adult patients.

“Although the results provide reassurance about the safety and tolerability of and immunogenicity conferred by repeat Tdap booster doses, advisory committees still need to determine the optimal interval for booster doses by using data provided by routine pertussis surveillance and outbreak evaluations,” they wrote.

Regarding the prospect of cost-effectiveness, investigators noted the observed models assumed an approximate patient duration of 10 years per dose. Therefore, the costs associated with a three- or four-year interval strategy for patient boosting is unclear, and the logistics of delivering such a program is “questionable.”

“In the United States, people who received their first Tdap vaccine dose as an adolescent are now approaching the age at which they are recommended to receive a decennial Td vaccine booster,” investigators wrote. “Some providers might find it convenient or necessary (eg, because of the availability of vaccine or during an outbreak) to give such a booster as Tdap.”

According to Sanofi, the US Centers for Disease Control and Prevention (CDC) currently recommends single-dose Tdap vaccine for both adults and adolescents, and for pregnant women during every pregnancy. Despite this guidance, nearly three-fourths of adults have not received the Tdap vaccine.

Earlier last month, Sanofi and Merck's joint hexavalent vaccine product Vaxelis was approved by the FDA for the vaccination of diphtheria, tetanus, pertussis, poliomyelitis, hepatitis B, and invasive disease due to Haemophilus influenza type b. Sanofi is currently the world leader in influenza vaccination distribution, having distributed about 70 million doses for this current flu season as early as August 2018.

In a statement accompanying the announced Tdap booster approval, David P. Greenberg, MD, Regional Medical Head of North America at Sanofi Pasteur, explained the need and value of a booster Tdap vaccine indication.

“While strong vaccination programs are in place for young adolescents, a single Tdap immunization does not offer lifetime protection against pertussis due to waning immunity," Greenberg said. "The licensure of Adacel as the first Tdap vaccine in the U.S. for repeat vaccination is an important step for eligible patients and offers flexibility for health care providers to help manage their immunization schedules."

The study, "Randomized Controlled Trial of the Safety and Immunogenicity of Revaccination With Tetanus-Diphtheria-Acellular Pertussis Vaccine (Tdap) in Adults 10 Years After a Previous Dose," was published online in the Journal of the Pediatric Infectious Diseases Society.