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Monday 24 June 2019
A case-control study about national outbreak of pertussis in England, 2011–2012

This week WAidid suggests to read "National Outbreak of Pertussis in England, 2011–2012: A Case-control Study Comparing 3-Component and 5-Component Acellular Vaccines With Whole-cell Pertussis Vaccines", an article published in May 2019 on the Oxford Academic Journal.


Whooping cough, a respiratory disease caused by Bordetella pertussis, remains a disease of global public health importance. Despite a significant reduction in global burden of disease following the introduction of routine whole-cell pertussis (wP) immunization in the 1950s, the disease remains endemic worldwide, with sporadic outbreaks and epidemic peaks observed every 2–5 years. Young unimmunized infants are at highest risk of severe complications and death from pertussis. Protection conferred either through vaccination or natural infection is not lifelong, and older vaccinated individuals can present with milder, often atypical symptoms, leading to delays in diagnosis and risk of transmission to unvaccinated children. In the 1970s, following concerns about the safety of wP vaccines, less-reactogenic acellular pertussis (aP) vaccines were developed. Acellular vaccines were first introduced into the routine UK immunization schedule in October 2001, as part of the preschool booster (PSB) dose, offered to children aged 3–5 years. Following a long period of good pertussis control, from 2011 an increase in laboratory-confirmed cases was observed across England. In the 2015 position paper, WHO concluded that the switch to aP vaccines contributed to a genuine resurgence of pertussis, and therefore it recommended to continue use wP for primary vaccination series.

The authors reported the data of a retrospective case-control study which compared the effectiveness of the aP vaccines currently licensed for the primary childhood immunization program in England (3-component acellular pertussis vaccine [aP3] and aP5) with the wP vaccines previously used, and the effectiveness of the different acellular PSB vaccines, in children aged 5 to 15 years, during the national outbreak in 2011 and 2012.

They reported that primary vaccination courses (3 doses of aP3) were more likely to be associated with disease than primary courses (3 doses of wP). There was no significant difference in protection among individuals who received 3 doses of aP5 and those who received 3 doses of wP, although the fact that aP5 cohorts were younger in age and therefore closer to vaccination limits the interpretation of this finding.

The authors highlighted that their study provides important evidence that priming with a aP5 vaccine might have a similar protective effect to the wP vaccine previously used in the accelerated UK schedule. Furthermore, as the type of pertussis vaccine used for PSB appears to have little impact on the overall protection, there remains greater flexibility over the choice of pertussis vaccine for booster doses.

AUTHORSCarlos F A Carvalho, Nick Andrews, Gavin Dabrera, Sonia Ribeiro, Julia Stowe, Mary Ramsay, Gayatri Amirthalingam.

To read the full article click here.