Vaccination Week, a campaign to promote the use of vaccines, which falls on April 24-30 this year, is also a time to celebrate. In China and elsewhere in the world, virtually every child is vaccinated, with phenomenal results: each year, 2.5 million newborn children are kept alive with a simple shot in the arm.

The most affordable method of disease control known to man, vaccines have eliminated previously terrible diseases such as smallpox, an illness that killed 500 million people in the 20th century alone. Following a global vaccination campaign, the World Health Organization (WHO) declared in 1980 that this killer disease had been eradicated. Today we are on the verge of wiping out polio, an infectious disease that can cause paralysis. Recently the WHO declared all of Southeast Asia to be polio-free, and although hard-to-reach pockets still exist, it is worth the effort required to consign polio to the dustbin of medical history.

Yet if smallpox is gone, and polio nearly so, why have other serious diseases not disappeared as well? Despite the overwhelming success of vaccines generally, barriers remain that prevent wider adoption which could save lives. One obstacle is simply inadequate access. For every five children saved by a vaccine, another three die because of a lack of access, especially to newer vaccines.

Even where access is not a problem, children sometimes fail to receive the complete course of vaccination needed for immunity. Many vaccines require two or three shots to be effective, yet parents forget to follow up; others cannot afford to take time off of work, or travel to vaccination centers. Some vaccines need refrigeration, and in remote locations where vaccines are delivered by truck, preserving the "cold chain" remains a challenge.

Misconceptions and misinformation pose barriers as well. Despite the well-documented efficacy of vaccines, some parents choose not to inoculate their children because of a false belief that vaccines are linked to autism, or because parents are inaccurately told that going through a life-threatening illness will improve their child's health in the long run. These misconceptions cost lives.

China has a rich history of innovation and invention. Hundreds of years before Englishman Edward Jenner pioneered the smallpox vaccine in 1798, Chinese were inoculating themselves against smallpox and other diseases. Writings published in 1549 show that powdered smallpox scabs were blown up the noses of healthy patients, who would then develop a mild case of the disease and be immune to it afterward. Still earlier evidence points to the year 1000, when a Chinese merchant inoculated his child with a needle dipped in dried smallpox residue.

In modern times, China has achieved remarkable success in eliminating vaccine-preventable diseases and accelerating the control of others. The country has eliminated maternal and neonatal tetanus; stopped the outbreak of wild poliovirus in just three months (the shortest time on record); and prevented 80 million infections of hepatitis B, as well as 20 million cases of chronic hepatitis. China is also rapidly moving towards the elimination of measles.