Regulatory Decision Summary for Adacel

Review decision

The Regulatory Decision Summary explains Health Canada’s decision for the product seeking market authorization. The Regulatory Decision Summary includes the purpose of the submission and the reason for the decision.


Product type:

Drug

Medicinal ingredient(s):

Tetanus Toxoid, Reduced Diphtheria Toxoid and Acellular Pertussis Vaccine Adsorbed

Therapeutic area:

Vaccinces

Type of submission:

Supplement to a New Drug Submission

Control number:

220103
What was the purpose of this submission?

 

The Supplement New Drug Submission (SNDS) was filed to obtain an indication for Adacel for vaccination during pregnancy for prevention of pertussis in young infants.

Adacel is currently indicated for active booster immunization for the prevention of tetanus, diphtheria and pertussis in persons 4 years of age and older.

The following additional indication has been approved:
Vaccination during pregnancy for passive immunization against pertussis disease in young infants.

 

Why was the decision issued?

 

Infants who have not been initiated vaccination before 3 months of age or completed the primary series of pertussis immunization are at high risk for pertussis infection. Vaccination with Adacel during the third trimester of pregnancy provided passive immunization against pertussis in infants until they are able to receive the pertussis vaccine beginning at two months of age.

The assessment of antibody responses and safety in the pregnant women and infants was based on published randomized/controlled studies with Adacel. A high level of pertussis antibody response was detected in the pregnant women after vaccination. The antibody levels were significantly higher in infants of Adacel vaccinated women at birth and 2 months of age compared to the control group.

In the infants of vaccinated women, the anti-PT levels (geometric mean antibody concentrations) were 54.2 (44.9-65.4) and 14.1 (11.5-17.2) IU/mL at birth and 2 months of age, respectively (while in the control group, the anti-PT levels were 9.5 (7.6-11.9) at birth and 3.6 (3.0-4.2) IU/mL at 2 months of age) achieving anti-PT levels greater than 10 IU/mL or 4-fold increase following passive immunization. Anti-PT levels greater than or equal to 10 IU/mL were considered to be clinically protective against severe disease.

This result was also supported by other randomized studies submitted.

It was also observed in the studies, when the infants received their primary series of pertussis immunization, the antibody level in the infants of Adacel vaccinated women were lower than the control group. There was no evidence that it leads to a greater risk of pertussis disease during the first year of life. The benefits of vaccinating during pregnancy and protecting a newborn outweigh the risks of blunting immune response to infants pertussis vaccination.

The effectiveness of vaccine in infants whose mothers were vaccinated with Adacel or Adacel-Polio during the third trimester of pregnancy was evaluated in three published observational studies. The results of the studies were consistent and these studies support the administration of Adacel or Adacel-Polio during pregnancy.

Adacel was well tolerated in pregnant women. The safety profile was consistent with previous reports. No vaccine-related serious adverse effects in the health of the fetus/newborn infants were reported from the published studies and no safety signal was identified from post marketing surveillance for pertussis maternal immunization.

The benefits of vaccinating during pregnancy and protecting the young infants outweigh the risks. Based on the clinical review and information from the published studies, the indication of "Vaccination during pregnancy for passive immunization against pertussis disease in young infants" is recommended for Adacel.

 

Decision issued

Approved; issued a Notice of Compliance in accordance with the Food and Drug Regulations.