Each year, 27 million children in poor countries do not receive basic preventive vaccines. As a result, serious diseases that were eliminated long ago in industrialized countries remain widespread in the developing world and cause more than 1 million child deaths annually.

Many of today’s childhood vaccines still require:

• Multiple dosages: Most vaccines must be given multiple times over weeks or months, posing a hardship for families who must travel long distances to the nearest health clinic.
• Refrigeration: Most vaccines must be constantly refrigerated, and many communities lack electricity. In 2007, an estimated 151 million vaccine doses delivered to developing countries will spoil without proper refrigeration.
• Delivery by injection: Most vaccines are delivered by injection, which increases the risk of transmitting HIV, hepatitis, and other infections through unsterile or reused syringes and needles. Needle-free vaccines could prevent an estimated 500,000 serious infections in 2007.

Recent advances in chemical engineering and other scientific disciplines could lead to a new generation of childhood vaccines that are effective after a single dose and do not require refrigeration or needles.