Pneumococcal vaccine effective in preventing severe pneumonia

Jun 16 2009

A new trial has found that pneumococcal vaccine is effective in preventing severe pneumonia, the leading cause of death among children in developing countries. Co-ordinated by the National Institute for Health and Welfare (THL) between 2000 and 2004, a large scale efficacy trial - first of its kind in Asia - was carried out in the Philippines to investigate the effect of an investigational pneumococcal vaccine.

A total of 12 190 children aged between six weeks and six months participated in the ARIVAC vaccine trial. The results showed that there was a 23 percent reduction in X-ray-confirmed pneumonia among children under two years of age who received the pneumococcal vaccine. However, the vaccine did not reduce clinically diagnosed pneumonia.

The children were given three doses of either a pneumococcal conjugate vaccine or placebo. At the same time, they were also given vaccines included in the Filipino national vaccination programme as well as a Hib vaccine. A subset of approximately thousand children was studied separately to analyse the ability of the vaccine to induce antibodies and prevent nasopharyngeal carriage of pneumococcus. The pneumococcal vaccine was highly effective in producing antibodies and proved to be a safe vaccine overall.

The results of this ARIVAC trial can be put to good use in pneumococcal vaccine development and in assessing the burden of disease of pneumococcal infections among children. The results can also provide robust support to decision-makers at a national level, especially in Asia. Despite the efficacy of the vaccine, price is still a big hurdle to overcome: for resource-poor countries that do not receive international financial aid, it may take several years if not decades before they can add the vaccine to the national vaccination programme.

Infections caused by the pneumococcus (Streptococcus pneumoniae) bacterium are the major causes of child mortality worldwide. The World Health Organisation (WHO) estimates that more than a million children die from pneumococcal meningitis and pneumonia every year. Furthermore, pneumococci cause a far greater number of minor respiratory tract infections. Severe infections can cause children to be at high risk for permanent hearing impairment, which in turn may lead to delays in development and learning difficulties. In the Philippines, pneumonia is the leading cause of severe morbidity and mortality among children under five years of age.

The ARIVAC vaccine trial in the Philippines received financial support from a number of sources, including the Academy of Finland, the Department of Development Co-operation of the Ministry for Foreign Affairs, the Finnish association of Physicians for Social Responsibility, the EU Directorate-General for Research, the US non-profit organisation PATH, and the WHO.

The trial was a joint venture of the international ARIVAC consortium, which consists of THL (Finland), the Research Institute for Tropical Medicine (the Philippines), the University of Queensland (Australia), the University of Colorado Denver (USA), and Sanofi Pasteur (France), the vaccines division of the sanofi-aventis Group.

According to Academy Research Fellow Hanna Nohynek at THL, one of the merits of the vaccine trial was the extent to which it fused together international research and development co-operation. "The pooling of funds from several different sources successfully ensured both the scientific quality of the research and the supply of local know-how and knowledge, in accordance with the principles of sustainable development," Nohynek said.

Full bibliographic information: Lucero MG, Nohynek H, Williams G et al.: Efficacy of an 11-valent pneumococcal conjugate vaccine against radiologically confirmed pneumonia among children less than two years of age in the Philippines: a randomized, double-blind, placebo-controlled trial. Pediatric Infectious Disease Journal, Volume 28, Number 6, June 2009: 455-462 www.pidj.com

Katherine L. O'Brien: Pneumococcal Vaccine and the Dance of the Veils Revealing Pneumonia Burden in Asia. Pediatric Infectious Disease Journal, Volume 28, Number 6, June 200: 464-465 (results commentary)