Authors:
Quinn HE, Snelling TL, Macartney KK, McIntyre PB
Authors notes:
Pediatrics 133(3): e513-e519.
Keywords:
effectiveness, immunization, pertussis, vaccine, waning
Abstract:
Data on the effectiveness of the diphtheria- tetanus-acellular pertussis (DTaP) vaccine in the first 4 years of life are sparse.
We evaluated the vaccine effectiveness (VE) of 1 and 2 doses of DTaP before 6 months of age and of 3 doses from 6 months of age in Australia, where, since 2003, a fourth dose is not given until 4 years.
We matched reported pertussis cases aged 2 to 47 months between January 2005 and December 2009 to controls from a population-based immunization register by date of birth and region of residence.
VE by number of doses and age group was calculated as (1 - odds ratio) x 100%.
VE against hospitalization increased from 55.3% for 1 dose before 4 months of age to 83.0% for 2 doses before 6 months.
The VE of 3 doses of DTaP against all reported pertussis was 83.5% between 6 and 11 months, declining to 70.7% between 2 and 3 years of age and 59.2% between 3 and 4 years of age.
DTaP provided good protection against pertussis in the first year of life from the first dose.
Without a booster dose, the effectiveness of 3 doses waned more rapidly from 2 to 4 years of age than previously documented for children >6 years of age who had received 5 doses.