Regulators used a re-analysis of data from an observational case-control study of Tdap vaccine effectiveness to show that Boostrix given in the third-trimester prevented pertussis among infants.
The FDA has approved GSK's Boostrix for immunization during the third trimester of pregnancy to prevent pertussis, commonly known as whooping cough, as a way to prevent infection in infants younger than two months of age.
“While vaccination is the best method for providing protection, infants younger than two months of age are too young to be protected by the childhood pertussis vaccine series,” Peter Marks, M.D., Ph.D., director of the FDA’s Center for Biologics Evaluation and Research, said in a press release. “This is the first vaccine approved specifically for use during pregnancy to prevent a disease in young infants whose mothers are vaccinated during pregnancy.”
Boostrix is composed of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine (Tdap). It was initially approved by the FDA in 2005 as a single dose for booster immunization against tetanus, diphtheria and pertussis in people 10 through 18 years of age. Later the FDA also approved Boostrix to include use in people 19 years of age and older and to include use of an additional dose 9 years or more after the initial dose of a Tdap vaccine.
The FDA’s approval of Boostrix has always included its use during pregnancy to protect the vaccinated individual. Today’s approval is specific to use in pregnancy to prevent pertussis in infants younger than 2 months of age. Since 2012, the CDC has recommended the use of Tdap vaccines during the third trimester of each pregnancy.
Regulators assessed the effectiveness of Boostrix to prevent pertussis among infants using a re-analysis of data from an observational case-control study of Tdap vaccine effectiveness. Data from 108 cases of pertussis in infants younger than 2 months of age and 183 control infants who did not have pertussis resulted in a preliminary estimate of Boostrix as 78% effective in preventing pertussis among infants when administered during the third trimester of pregnancy. This preliminary estimate of effectiveness was updated using data from published observational studies. These statistical analyses provided estimates of effectiveness that are consistent with the preliminary estimate of 78%.
The safety of Boostrix administered during the third trimester of pregnancy was assessed in a randomized, placebo-controlled study with a non-U.S. formulation of Boostrix. In previous clinical studies, the most commonly reported side effects by individuals who received Boostrix were pain, redness at the injection site, headache, fatigue and gastrointestinal symptoms.