At its debut 2 years ago, a vaccine that pre-vents cervical cancer was heralded as a public health breakthrough that could poten-tially save millions of women’s lives. Yet although the vaccine is now given routinely to young girls in the United States and Europe, it hasn’t been deployed in poorer countries, where it could make a bigger difference. This week at a meeting* in Mexico City, health officials and researchers are launching a campaign to introduce the vaccine in Latin America, the first region in the developing world likely to benefit.

Many issues are unresolved, including whether health care systems are ready for the vaccine and whether conservative groups will oppose it. The biggest hurdle, however, is cost. Conference organizers hope that with new data on human papillomavirus infection and the vaccine’s potential benefits, Latin American health officials can persuade their governments to negotiate with the two com-panies that manufacture HPV vaccines to lower the price, now $360 for three doses. The meeting will “send a strong message” about demand, says epidemiologist Jon Andrus of the Pan American Health Organization (PAHO) in Washington, D.C., a cosponsor.

Cervical cancer is associated with HPV, the most common sexually transmitted disease. Clinical trials have shown that two HPV vaccines, made by Merck and GlaxoSmithKline (GSK), are at least 95% effective in prevent-ing persistent HPV infection by the two main types that cause cervical cancer (HPV-16 and HPV-18) (Science, 29 April 2005, p. 618). Because screening using Pap smears— catches most cervical cancer in industrialized countries, the HPV vaccines won’t make much of a dent in cancer cases. But disease is much more common in the developing world, where screening often falls short. About 85% of the 270,000 deaths from cervical cancer each year occur in these countries.

To prepare for the Mexico meeting, an international team of researchers pooled data from 15 years’ worth of studies on HPV in Latin America and the Caribbean. Their meta-analysis of 118 studies, including data on 33,000 healthy women, found that the HPV infection rate averages 19%, with wide varia-tion—from 13% in Mexico to twice that in Costa Rica. (Prevalence is 27% in the United States.) Women with cervical cancer were almost invariably infected with HPV; HPV-16 and HPV-18 accounted for 59% of cases in the region. That means that the Merck and GSK vaccines could prevent 500,000 deaths if given over 10 years to 70% of 12-year-old girls, the researchers found.

Health officials in the developing world are questioning whether they can afford the price. HPV vaccination would reduce the bur-den of cancer treatment and cut back on screening, a woman might need to be tested three times in her lifetime, the analysis by the international team notes. Even so, the benefits would be worth the costs only if the vac-cine’s price comes down. Even at $25 for the three doses, adding HPV vaccine to the standard inoculation regime would cost $290 mil-lion over 5 years.

Health experts expect that the companies will offer a discount, as they did in 2005 when they agreed to bulk sales of a new rotavirus vaccine aimed at preventing child-hood diarrhea (Science, 24 September 2004, p. 1890). First, the World Health Organization (WHO) would need to prequalify the vaccines based on information submitted last year by the manufacturers. Then PAHO could begin negotiating.

If Latin American countries buy the vaccine, they will move on to the challenge of getting it to young girls. This group is older than the one that receives traditional childhood vaccines, so health officials will likely introduce the HPV vaccine in schools. Latin America is up to the challenge, says Ciro de Quadros, executive vice president of the Sabin Vaccine Institute in Washington, D.C., and one of the meeting organizers. He points to the region’s success with other vaccines, including nearly eradicating rubella since 1998 by vaccinating people up to 40 years old. “We hope HPV will be the same,” he says.

It’s still unknown whether the HPV vaccine will draw opposition, as it did in the United States. Some U.S. religious groups initially opposed it as condoning sexual activity by girls. But once the vaccine was widely introduced, notes Scott Wittet of the Seattle, Washington based Program for Appropriate Technology in Health, those opponents had little influence. In a pilot project to explore introducing the HPV vaccine in Vietnam, Uganda, India, and Peru, this form of opposition has not been a problem so far, says Wittet. “Once people understand the issues, it’s not a hard sell.”

WHO will likely issue its decision on pre-qualifying the two vaccines within a few months, Andrus says. Also later this year, WHO and PAHO advisory councils will discuss guidelines on administering HPV vaccines. Assuming that they issue strong recommendations, Andrus says, price negotiations should soon follow.

* Towards Comprehensive Cervical Cancer Prevention and Control, Region of the Americas, 12-13 May, 2008, Mexico City, Mexico