Pneumococcal disease is the leading vaccine preventable cause of child deaths worldwide. WHO estimates that about 1.6 million people, including up to 1 million children under five years old, die every year of pneumococcal pneumonia, meningitis, and sepsis.(1) In populations with high child mortality rates, pneumonia is the leading infectious cause of mortality and accounts for about 20-25 percent of all child deaths.(2)
Recognizing the heavy burden of pneumococcal disease in young children and the safety and efficacy of the PCV7 in this age group, WHO considers its inclusion in national immunization programmes as a priority, particularly in countries with under five mortality greater than 50 per 1,000 live births, or greater than 50,000 child deaths annually.
"Pneumococcal disease kills up to a million children a year, most of them in developing countries," said Dr. Adenike Grange, president of the International Pediatric Association. "This decision is an important step in the introduction of a safe and effective pneumococcal vaccine for developing countries."
Dr. Orin Levine, executive director of PneumoADIP -- a non-governmental organization that aims to shorten the time between use of a vaccine in industrialized nations and their introduction in the developing world commented, "GAVI's PneumoADIP(3) applauds WHO for providing important leadership and guidance for the use of pneumococcal vaccine to prevent pneumonia in developing countries. Together with GAVI's financing and the Advance Market Commitment, the WHO position statement is helping bring pneumococcal vaccines to the children who need them most, faster than ever before."
Typically new vaccines take fifteen years or more to reach developing countries. With this recommendation there is now the prospect of pneumococcal conjugate vaccine achieving regular use in Africa only eight years after it was introduced in the U.S.
HIV infection significantly increases the risk of pneumococcal disease in children and adults. Since pneumococcal conjugate vaccines have been shown to be safe and efficacious in HIV infected children, WHO recommends that countries with high prevalence of HIV prioritize the introduction of PCV7. Furthermore, populations with high prevalence of other underlying conditions that increase the risk of pneumococcal disease, e.g. sickle cell disease, should also be targeted for vaccination.
"Children with HIV are up to 40 times more likely to get pneumococcal disease than HIV-negative children and the vaccine has been shown to help prevent the disease in these vulnerable children" said Dr Thomas Cherian, coordinator of the Expanded Programme on Immunization Plus, WHO Department of Immunization, Vaccines and Biologicals.
The serotypes included in the PCV7 vaccine cover 65-80 percent of the serotypes associated with invasive pneumococcal disease among young children in Western industrialized countries. Despite the absence of some serotypes that are important causes of pneumococcal disease in developing countries, PCV7 can prevent substantial mortality and morbidity in these countries. The safety and efficacy of PCV7, as with other formulations of pneumococcal conjugate vaccines, have been well established in numerous settings both in: industrialized and developing countries; in urban and rural settings; and among infants with HIV infection.
"As a result of this recommendation, we expect pneumococcal vaccines to begin saving lives in GAVI countries in 2008. GAVI countries now have WHO's recommendation and the ability to obtain the vaccine through GAVI for $0.10 to $0.30 per dose," said Levine. "Recognizing that vaccines with 10-13 serotypes will become widely available by 2010, WHO advises countries to start saving lives with the available vaccine and then decide whether to switch to one of the other vaccines when they arrive," said Levine.
The WHO recommendation along with WHO pre-qualification of PCV 7 will set the stage for the introduction of this vaccine with GAVI support in the world's poorest countries in 2008. Pre-qualification is a WHO procedure to guarantee the safety and efficacy of all vaccines purchased by the UN agencies.
Introduction of any new vaccine requires careful attention to surveillance and pneumococcal vaccine is no exception. WHO encourages countries to conduct appropriate surveillance for pneumococcal invasive disease to establish the baseline and monitor the impact of vaccination, including the occurrence and magnitude of replacement disease. This is particularly important in developing countries that are among the first to introduce vaccine into their national programs and in countries with high prevalence of HIV infections, or other conditions known to increase the risk of pneumococcal disease.
Pneumococcal disease affects persons of all ages. The risk of serious disease remains high throughout the first 24 months of life. When PCV7 is first introduced into routine childhood immunization programs, maximum individual and community-level protection can be achieved by also providing a single catch-up dose of the vaccine to previously unvaccinated children aged 12-24 months, and to high-risk children aged 2-5 years.
Other pneumococcal vaccines in development, which contain additional serotypes targeting strains of the disease that commonly cause death and disability in the developing world, are in advanced stages of testing and are expected to become available to developing countries between 2009 and 2011. Introducing the 7-valent vaccine now means that lives can start to be saved straight away. This vaccine, manufactured by Wyeth, is effective, well-tolerated and can be delivered through existing immunisation systems. Surveillance data from the USA(4) indicate that the herd immunity(x) effect from routine childhood pneumococcal vaccination prevents twice as many cases as the direct effects of vaccination alone, protecting vulnerable adults as well as children.
(x) Herd immunity is the resistance of a population to spread of an infectious organism due to the immunity of a high proportion of the population -- the U.S. study suggests that the herd immunity effect of pneumococcal vaccination may be particularly strong.
1. World Health Organization. Pneumococcal vaccines. Wkly Epidemiol Record 2003;14:110-19
2. Williams BG, Gouws E, Boschi-Pinto C et al. Estimates of worldwide distribution of child deaths from acute respiratory infections. Lancet Infect Dis 2002;2:25-32
3. Pneumococcal Vaccines Accelerated Development and Introduction Plan - funded through a $30 million grant from the GAVI Alliance
4. Centers for Disease Control and Prevention. Direct and Indirect Effects of Routine Vaccination of Children with 7-Valent Pneumococcal Conjugate Vaccine on Incidence of Invasive Pneumococcal Disease - Unites States, 1998-2003. MMWR 2005;54:893-897.
Source: World Health Organization