摘要：Infectious diseases are responsible for approximately 25% of global mortality, especially in children aged younger than 5 years. Much of the burden of infectious diseases could be alleviated if appropriate mechanisms could be put in place to ensure access for all children to basic vaccines, regardless of geographical location or economic status. In addition, new safe and effective vaccines should be developed for a variety of infections against which no effective preventive intervention measure is either available or practical. The public, private, and philanthropic sectors need to join forces to ensure that these new or improved vaccines are fully developed and become accessible to the populations in need as quickly as possible. THE IMPLEMENTATION OF large-scale and comprehensive national immunization programs, and the considerable successes that were achieved in the eradication of smallpox and the reduction of polio, measles, pertussis, tetanus, and meningitis, were among the most notable achievements of the 20th century. Even in the poorest countries, it has been possible to achieve significant progress in disease control by immunization. 1 There is good reason to expect that these advances will be sustained and will progress even further in the 21st century. 2 However, the world’s poorest regions are still suffering a heavy toll of premature deaths and disabilities from infectious diseases for which vaccines do not exist, or need to be improved. 3 Infectious diseases are still responsible for at least 15 million deaths per year, making them the largest contributors to the disparity in average life span between rich and poor countries (77 and 52 years, respectively). In addition to this high death toll, millions of children are suffering from disability and illness because they have not been properly immunized. The most effective way to reduce disease and deaths from infectious diseases is to vaccinate populations at risk. Unfortunately, vaccines are still missing for a number of pathogens, and some of the existing vaccines are not completely protective. For these diseases, it is of crucial importance that research and development of vaccines be a priority. The following is an overview of a few selected fields of current vaccine development.
