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CSU 41/2011: PERTUSSIS VACCINES/ VACCINS ANTICOQUELUCHEUX

Monday, 7th of February 2011 Print

 

 

WHO has recently issued an updated position paper on pertussis vaccines, available in French and English at http://www.who.int/wer/2010/wer8540.pdf

 

Most developing countries use the whole cell pertussis vaccine. Those interested in this vaccine may wish to read the excerpts below.

 

Good reading.

 

BD

 

From WHO Position Paper on Pertussis Vaccines, Weekly Epidemiological Record, October 2010

 

Immunogenicity, efficacy and effectiveness whole-cell pertussis vaccines

 

The immune response to wP vaccines is directed against an array of antigens of whole bacterial cells. Significant differences in the immune responses to various antigens have been observed among the different wP vaccines. A systematic review18 of the effects of pertussis vaccines included 49 randomized controlled trials and 3 cohort studies, and used the WHO case definition of pertussis;19 the review found that the pooled efficacy of wP vaccine against pertussis in children was 78%, but efficacy varied significantly among vaccines. The efficacy of wP alone ranged from 61% (relative risk [RR], 0.39; 95% CI, 0.27–0.57) to 89% (RR, 0.11; 95% CI, 0.08–0.15); the efficacy of diphtheria–tetanus–whole-cell pertussis (DTwP) vaccines ranged from 46% (RR, 0.54; 95% CI, 0.46–0.63) to 92% (RR, 0.08; 95% CI, 0.05–0.13). In New South Wales, Australia, the efficacy of wP was highest (91%) among children aged 8–23 months and lowest (78%) among children aged 9–13 years.20 A randomized double-blind trial in Senegal showed that 3 doses of a French wP vaccine had an overall efficacy of 55% against pertussis (defined as ≥21 days of cough, with pertussis confirmed by culture, serology or contact with a cultureconfirmed person) versus 96% for the stricter WHO case definition (≥21 days of paroxysmal cough in addition to the same confirmative criteria).21

 

The protective impact of an incomplete series of wP immunization using wP-containing vaccines was calculated in a few trials: in a study in the United States a single dose of wP provided an estimated efficacy of 44%, and 4 doses provided an estimated efficacy of about 80% against typical paroxysmal cough.22 A study from Denmark estimated that 1 dose had an efficacy of 36% in preventing hospitalization, and 3 doses had an efficacy of 87%.23

 

Little is known about the effectiveness of wP among older age groups because pertussis was previously perceived as a problem only of young children. Also, the reactogenicity of wP vaccine was thought to be too high to permit routine use in older children, adolescents and adults.

 

After 30 years of use in France, wP vaccines continued to be highly effective although B. pertussis still circulated

in the community.24 On the other hand, surveillance data from Poland indicated a decrease in wP effectiveness

during 1996–2001: during this time vaccine efficacy in children aged 2–5 years decreased from 97%

to 73%, and in children aged 6–9 years, efficacy decreased from 84% to 69%.25

 

Comparing the efficacy of wP-containing and aP-containing vaccines

 

The efficacies of aP and wP vary depending upon the case definition of pertussis used. However, the best aP vaccines have higher efficacy than low-efficacy wP vaccines but they may be less efficacious than the highest-efficacy wP vaccines in preventing whooping cough.21, 29, 30, 37



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