New horizons for vaccines

New vaccines hold potential to avert disease

Vaccination may be the most effective public health intervention of all time. Because of vaccines, smallpox has been eliminated globally; poliomyelitis eradication is nearly complete; and in regions where people are routinely vaccinated, diseases such as measles, diphtheria, tetanus, and Haemophilus influenzae type b (Hib) are no longer the threat they once were. Vaccination, it is estimated, prevents more than 2.5 million deaths each year.

Vaccines protect against disease by inducing immunity. In general, they contain the antigens or parts of the antigens that cause diseases in a killed or weakened state. The antigens in vaccines are not strong enough to cause symptoms of the targeted disease, but they are strong enough to induce the immune system to produce antibodies against it.

A need for new R&D

While the history of vaccines is studded with victories, there are still many diseases for which vaccines have not been developed or are not widely available. Some of them are well known: malaria, pandemic influenza, and AIDS. Other diseases are less familiar but potentially just as deadly, especially in the developing world. Diarrheal disease, for example, kills approximately 1.8 million children worldwide each year. Pneumonia kills 2 million and is the leading cause of death in children younger than 5 years in the developing world.

Serious challenges to the development of safe and effective vaccines remain. Researchers must identify suitable antigens, adjuvants, and delivery methods. Once developed, new vaccine candidates face substantial regulatory, manufacturing, and distribution hurdles.

Recently, however, a number of vaccines have begun moving from the laboratory toward the health clinic. For example, the Phase 3 trial of RTS,S—the most clinically advanced vaccine candidate against malaria—is under way in sub-Saharan Africa, igniting hope for a new tool against a disease that kills approximately 900,000 people every year.

For more information on the above data, see:

World Health Organization. Expanded Programme on Immunization (EPI).
US Centers for Disease Control and Prevention. How vaccines prevent disease.
PATH. Developing New Vaccines Against Diarrheal Disease (137 KB PDF).
PATH. Developing New Vaccines Against Pneumonia (67 KB PDF).
PATH. Phase 3 malaria vaccine trial begins—final testing of RTS,S.