Pertussis Immunization Programs in Low Income Countries (PERILIC)

March 21, 2022 updated by: Institut Pasteur

Due to waning of infectious as well as vaccine immunity and lack of vaccination boosters, a large number of adolescents and adults are no longer immunized against Bordetella pertussis, the agent of whooping cough and consequently may contract whooping cough. Furthermore, these populations represent a reservoir of the infectious agent from which the dissemination to non-immune infants is possible, causing severe illness, or even death, in this age group.

Few studies have been carried out on whooping cough in developing countries (incidence, contaminator's age, etc.) and, specifically, none have assessed the duration of protection induced by the whole cell pertussis (wP) vaccine mainly presently used in these countries.

However, data on the duration of vaccine induced protection are essential to determine i) the usefulness of vaccine boosters and ii) the target age group for these boosters.

The aims of the present study are:

  • To evaluate the proportion of confirmed pertussis cases in infants presenting whooping cough syndrome (WP1a)
  • To evaluate the proportion of confirmed pertussis cases or healthy carriers among contact cases
  • To determine origin of the infant's contamination (WP1b)
  • To determine the duration of protection induced by the wP vaccines used in contact cases and the child population aged 3 to 15 yo (WP1b and WP2)
  • To bring new scientific evidences documenting the potential need for initiating boosters (WP1b and WP2)
  • To allow a comparison of the results with those obtained using the same methodology for the acellular pertussis vaccine and/or in other contexts. Potential implications for the use of pertussis vaccines in low and moderate income countries.
  • To increase local capabilities by the transfer of materials and expertise that will make the diagnosis of pertussis possible in the centres of reference and strengthen a pertussis monitoring network in the implicated countries.
  • To improve children's health through a better match of the vaccination schedule according to the reality of the situation.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Background:

Vaccination of infants and young children with a whole-cell pertussis (wP) vaccine dramatically decreased the mortality and morbidity due to B. pertussis. However, twenty-five years of "honeymoon" period, after the introduction of high vaccination coverage, reappearance of whooping cough cases in industrialized countries was observed in infants contaminated by adolescents and adults. This modification in transmission of the disease after the introduction of the wP vaccine indicated that the immunity provided by the vaccine is not lifelong, just like that provided by natural infection, and that it decreases7-9 years after the first vaccination and the first booster. Due to secondary effects, wP vaccines cannot be used for boosters. Moreover, the wP vaccines have been shown to be different in terms of efficacy (varying from 30 to 95%). Acellular pertussis (aP) vaccines consisting of purified and inactivated bacterial proteins, have therefore been developed and commercialized. These vaccines induce much fewer side effects and may therefore be used for primary-vaccination as well as for vaccine boosters. They are expensive but have more reproducible manufacturing. The humoral and long-term cell-mediated immunities granted by the aP vaccines have been shown to be comparable to the immunity granted by the wP vaccines, effective for 6-7 years after the booster vaccine in the second year of life, also inducing different cell immunity. Since 2007, the proportion of B. pertussis and B. parapertussis isolates no longer producing vaccine antigen(s) has increased in the industrialized countries that use aP vaccines. These isolates may decrease the efficacy of the aP vaccines. Does this type of isolates circulate in the Low income countries still using wP vaccines ? Does it reduce the efficacy of the wP vaccines? Moreover, the wP vaccines used in the Southern countries have not been assessed like the ones used in the Northern countries. In particular, the duration of protection after the primary-vaccination and a vaccine booster is not known.

Rational:

For various reasons, a large difference exits between the monitoring systems across the world: awareness of the disease is variable depending on the population; differences in the immunization coverage and strategies; diverse compositions of the vaccines used; but overall the large differences between the vaccines in terms of immunity against the disease, protection against infection and/or decrease in the transmission of the pathogen. The underestimation of pertussis is recognized by the World Health Organisation (WHO) and the (Global Pertussis Initiative) who highlight the problem of the reliability of the declared data.

This situation is the result of i) limited use of biological diagnostics (problems in isolating the bacteria in the laboratories); ii) diagnostic errors due to the fact that diagnosis is mainly clinical ; iii) inadequate monitoring of the illness ; iv) a lack of awareness among physicians. Pertussis is not considered when it is comes to identifying the respiratory pathogen: most clinicians continue to consider it as only a child illness and ignore adult infections. The absence of an available tool allowing a reliable diagnostic to be made makes difficult to assess the real impact of this pathogen in child respiratory syndromes.

Several studies have been performed on the duration of protection induced by the wP and aP vaccines in Australia, the USA and in Europe. However, few studies have been performed on the wP vaccines used in middle and low income countries and none in Cambodia, Madagascar and Togo. This is one of the objectives of our study. This will allow the vaccination strategy of each region concerned to be adapted when needed, as recommended by the WHO.

Expected Outcomes:

Impact on vaccination strategy:This study, as well as the analysis of data from other national programs for the surveillance of Pertussis, may raise public health authorities' awareness and help them adapting their assessment method for national vaccination programs by including the duration of protection induced by their national wP vaccine and their data on vaccine coverage, on the basis of the information in vaccination booklets, as recommended by WHO.

Impact on the improvement the children's health: The results of our study should raise the public health authorities' awareness on vaccine-preventable diseases, especially whooping cough. This raising of awareness will focus on the surveillance/monitoring and diagnosis of this disease. Moreover, the development of reliable biological diagnostic tools for pertussis will help the clinicians to confirm pertussis diagnosis and to adapt the therapeutic approach accordingly, thus improving the care of the infected person and to stop transmission of the disease which is very contagious.

Impact on the surveillance of the disease by developing an hospital-based surveillance,Training, technology transfer and strengthening of the surveillance network: For the first time, the detection and identification techniques for the other species of Bordetella genus (i.e. B. parapertussis and B. holmesii) will be transferred to laboratories in low income countries. The diagnosis of the different Bordetella species by real time polymerase chain reaction (RT-PCR) and the measure of anti-pertussis toxin Immunoglobulin G (IgG) level by serological tests will be set up in the laboratories participating in this study. These laboratories could further be used by the national surveillance network and thus improve the quality of the data available for the local health authorities and for WHO. Thus, this study will allow the establishment of an effective monitoring of pertussis in the countries participating in the study through the raising of the population's awareness, the training of local doctors on the clinical screening of this disease, and finally via the transfer of diagnostic techniques within the laboratories.

Study Type

Observational

Enrollment (Actual)

3587

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Cambodia
      • Phnom Penh, Cambodia
        • Institut Pasteur of Cambodia
  • Madagascar
      • Antananarivo, Madagascar
        • Institut Pasteur de Madagascar
  • Togo
      • Dapaong, Togo
        • Agence de Médecine Préventive

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Probability Sample

Study Population

Cohort 1 (WP1a): Infants under 6 months old coming to hospital with clinical signs of whooping cough syndrome.

Cohort 2 (WP1b): Contact cases of confirmed infants included in the WP1a module

Cohort 3 (WP2): Children from 3 to 15 years old included, without underlying illness, with complete pertussis primo-vaccination

Description

Inclusion Criteria:

Cohort 1 (WP1a)

  • Infants under 6 months old
  • Presenting clinical signs of a whooping cough syndrome
  • Written consent obtained from a parent/guardian of the child

Cohort 2 (WP1b)

  • People in regular and prolonged contact (>1h per day) with the index case for at least 5 days before the signs of whooping cough occurred in the infected child, living (or not) in the same household.
  • For the adults, written consent obtained.
  • For minors under 7 yo: written consent obtained from a parent/guardian.
  • For minors over 7 yo: written consent obtained from parent/guardian and oral assent obtained from the child.

Cohort 3 (WP2)

  • Child aged between 3 and 15 yo
  • Up to date first pertussis vaccination (vaccination booklet or official register)
  • Last pertussis vaccination done more than one year before inclusion
  • For minors under 7 yo: written consent obtained from parent/guardian.
  • For minors over 7 yo: written consent obtained from parent/guardian and oral assent obtained from the child.

Exclusion Criteria:

Cohort 3 (WP2)

- Pertussis vaccination done more than one year before inclusion

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort
Intervention / Treatment
Seroepidemiological cohort (WP2)

Children between 3 and 15 years old with complete primo-vaccination against B.Pertussis

Blood sampling:

A blood sample collected by fingerprick
Procedure: Blood Sampling
Blood sample by the tip of a finger (fingerprick)
Index case (WP1a)

Infant under 6 months old with clinical signs of whooping cough syndrome.

Nasopharyngeal sampling:

A nasopharyngeal sample collected from each nostril by aspiration or swabbing
Procedure: Nasopharyngeal sampling
Nasopharyngeal sample by aspiration or swabbing
Control case (WP1b)

Contact cases of infant with a positive diagnosis for whooping cough.

Nasopharyngeal sampling:

A nasopharyngeal sample collected from each nostril by aspiration or swabbing

Blood sampling:

A blood sample collected by fingerprick
Procedure: Blood Sampling
Blood sample by the tip of a finger (fingerprick)
Procedure: Nasopharyngeal sampling
Nasopharyngeal sample by aspiration or swabbing

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Proportion of biologically confirmed cases of pertussis in patients under 6 months old admitted into hospital with clinical signs corresponding to whooping cough syndrome.
Time Frame: November 2018
Primary Outcome of WP1a (Cohort 1)
November 2018
Proportion of cases tested positive for B.Pertussis given by the presence of B. pertussis DNA in the nasopharyngeal sample or by the presence of an anti-pertussis toxin IgG level >100 IU/mL in the serum.
Time Frame: November 2018
Primary Outcome of WP1b (Cohort 2)
November 2018
Proportion of cases tested positive given by the presence of an anti-pertussis toxin IgG level >100 IU/mL in the serum.
Time Frame: November 2018
Primary Outcome of WP2 (Cohort 3)
November 2018

Secondary Outcome Measures

Outcome Measure
Time Frame
Estimation of the relative risk of the disease occurring in the contact patients based on their immunization status and age groups
Time Frame: April 2019
April 2019

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Institut Pasteur

Collaborators

Agence de Médecine Préventive, France
Institut Pasteur de Madagascar
Institut Pasteur, Cambodia

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 22, 2017

Primary Completion (Actual)

July 25, 2019

Study Completion (Actual)

December 31, 2019

Study Registration Dates

First Submitted

November 17, 2016

First Submitted That Met QC Criteria

December 2, 2016

First Posted (Estimate)

December 6, 2016

Study Record Updates

Last Update Posted (Actual)

April 1, 2022

Last Update Submitted That Met QC Criteria

March 21, 2022

Last Verified

July 1, 2021

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2015-055

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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