WEDNESDAY, Feb. 6 (HealthDay News) -- Pertactin-negative variants of Bordetella pertussis have been identified in the United States; and children who receive diphtheria-tetanus-whole-cell pertussis (DTwP) priming have lower reported rates of pertussis, according to correspondence published in the Feb. 7 issue of the New England Journal of Medicine.

Noting an increase in the numbers of cases of pertussis in several countries, including the United States, despite increased vaccination, Anne Marie Queenan, Ph.D., from Janssen Research and Development in Raritan, N.J., and colleagues examined the contribution of pertactin-negative variants of B. pertussis. The researchers found that 11 of 12 isolates of B. pertussis cultured from specimens from children hospitalized in Philadelphia were negative for pertactin.

Juventila Liko, M.D., M.P.H., from the Oregon Health Authority in Portland, and colleagues examined the effectiveness of first-dose DTwP priming in children fully immunized with diphtheria-tetanus-acellular pertussis (DTaP) beyond their first year or life and in those who received a DTaP booster. Using data from April 1997 through July 2012, 484 cases of pertussis were reported, 402 of which were matched to the Oregon immunization information system ALERT IIS. The researchers found that the reported rates of pertussis were lower among children who had started the vaccination process with DTwP. Higher rates of reported pertussis were seen for children who underwent priming with acellular versus whole-cell pertussis.

"The balance between vaccine side effects and effectiveness needs to be considered in developing and implementing recommendations on pertussis vaccination, particularly in light of recent outbreaks of pertussis," Liko and colleagues write.

Full Text - Queenan
Full Text - Liko