| Pneumococcal vaccines
responsible officer: Dr
Thomas Cherian
Prevention of pneumococcal disease by vaccination is one
of the approaches to control the high rates of morbidity and mortality due to this
organism. A polyvalent polysaccharide vaccine has been available for several years but
this vaccine is poorly immunogenic in children, who are at highest risk for invasive
disease, and does not result in immunological memory. A 7-valent glycoprotein conjugate
vaccine has recently been licensed for use in children in the United States. Several new
conjugate vaccines containing 9 or 11 serotypes of pneumococcus are undergoing trials,
some of which are in developing countries. Other candidate vaccines using protein antigens
that are common to all pneumococci, are also in the early phases of clinical trials. These
vaccines, if efficacious, will have a very important role in reducing mortality in
developing country populations. WHO has an important role in promoting research to
evaluate and planning strategies for introduction of these vaccines in developing country
populations.
Pneumococcal Conjugate Vaccines
Ongoing efficacy trials
The WHO has played an important role in the monitoring of
the ongoing efficacy trials of the pneumococcal conjugate vaccine in South Africa, The Gambia and the Philippines through the
steering committees and DSMB. In addition, WHO is also a principal sponsor of the efficacy
trial in The Gambia.
Standardisation of data collection
WHO has also been the focal point for three activities
that aim to standardise procedures to collect data on key outcomes across the various
trials to ensure that comparable data are collected at each site in a standardised manner.
This effort is critical to the interpretation of these data. These efforts include:
- Standardisation of radiological diagnosis of pneumonia
- Standardisation of procedures to study nasopharyngeal
carriage of pneumococcus
- Standardisation for estimating cost-effectiveness of
immunisation.
Additional studies
In addition, WHO is supporting or planning to support
studies to evaluate the glycoprotein conjugate vaccines in newborn infants and those
infected with HIV. WHO also plans to support studies evaluating alternative vaccination
schedules with conjugate vaccines.
The GAVI Pneumococcal Vaccine Accelerated
Development and Introduction Plan (ADIP)
In 2003 GAVI launched the Accelerated Development and
Introduction Plan (ADIP). This is an initiative to facilitate the introduction of
pneumococcal conjugate vaccines in developing countries. The Johns Hopkins Bloomberg
School of Public Health, Baltimore has been selected as the host institution and WHO will
be a key partner in this effort.
Pneumococcal common protein vaccines
Two potential problems associated with the pneumococcal
conjugate vaccine that have been identified earlier were the limited protection due to
serotype specificity and the high cost of the vaccine. Another strategy to overcome these
problems would be the use of common protein vaccines. These proteins are common to all
serotypes of Pneumococcus and appear to be immunogenic and protective in animal models.
They are also likely to be less expensive to manufacture than the polyvalent vaccines
which use the capsular polysaccharide as the immunising antigen since they can be produced
in large amounts using inexpensive recombinant technology. Thus, they have a greater
potential for use in developing countries with high burden of disease and limited
resources.
WHO's role would be to accelerate the development
and evaluation of these vaccines and facilitate and support human trials at developing
country sites.
...read more about
pneumococcal vaccines
Updated April 2003 |
