Duration of Protection After First Dose of Acellular Pertussis Vaccine in Infants.
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) × 100%.
VE against hospitalization increased from 55.3% (95% confidence interval [CI], 42.7%-65.1%) for 1 dose before 4 months of age to 83.0% (95% CI, 70.2%-90.3%) for 2 doses before 6 months. The VE of 3 doses of DTaP against all reported pertussis was 83.5% (95% CI, 79.1%-87.8%) between 6 and 11 months, declining to 70.7% (95% CI, 64.5%-75.8%) between 2 and 3 years of age and 59.2% (95% CI, 51.0%-66.0%) 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.
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ABSTRACT: The USA is experiencing a pertussis resurgence that resulted in a 60-year high of 48,000 cases in 2012. Our ability to counteract this resurgence is hampered by the fact that pertussis pathogenesis and immunity to pertussis infection are not well studied. Studies in humans are difficult due to the low frequency of pertussis in the population, the cyclical nature of incidence and the sporadic geographic distribution of cases. While existing animal models reproduce many aspects of pertussis, none of them adequately reproduces the full spectrum of disease. We describe the baboon model of pertussis. The baboon model is the first animal model that recapitulates the full spectrum of human pertussis including coughing and transmission. This model is being utilized to examine pertussis pathogenesis and host responses to infection and vaccination. It is likely the baboon model will provide an important tool in the development of improved pertussis vaccines.Expert Review of Vaccines 09/2014; · 4.22 Impact Factor
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ABSTRACT: The recent epidemics of pertussis (whooping cough) in parts of the USA and Australia have led to the largest numbers of annual cases reported in over half a century. These epidemics demonstrated a new pattern, with particularly high rates of disease among pre-adolescents and early adolescents. These high rates of pertussis coincided with the first cohorts vaccinated with purely acellular pertussis vaccine, which replaced whole-cell pertussis (wP) vaccine in the later 1990s in the USA and Australia. Studies undertaken during these epidemics provide new evidence of more rapid waning of acellular pertussis-containing vaccines and longer-term protection from effective wP-containing vaccines. There is evidence that receiving wP as at least the first dose of pertussis-containing vaccine provides greater and more long-lived protection, irrespective of the nature of subsequent doses. This evidence will be reviewed together with the immunobiology associated with both vaccines, and the implications for pertussis control discussed.Expert Review of Vaccines 08/2014; · 4.22 Impact Factor