Injection of hope

19.11.31: A MASS immunisation programme against Aids begins in Uganda next month.

Not only has the new vaccine cut infection rates by 70% in trials but it costs one-tenth of conventional inoculations.

"This could spell the end of Aids," says Jang Pak Sing, the United Nations health director. Besides the low cost, the vaccine does not require refrigeration or special storage.

Aids has caused an estimated 100m deaths this century. More than half have been in sub-Saharan Africa, although deaths in China have risen steeply in the past 10 years. Once the scourge of the West, it now affects less than 1% of the population in Europe and the US thanks to continuing public health programmes.

Uganda was one of the first African countries to tackle the problem. "We are hoping to eradicate it in Uganda," says Jang. "The low price means that inoculation programmes are feasible in poorer nations."

Conventional vaccines use a dead or modified virus to trigger the immune system. The new vaccine uses genetic information from the virus's ribonucleic acid (RNA) instead.

"Developing an Aids