In an April 7 opinion column, Drs. Homayoon Khanlou and Michael Weinstein of the AIDS Healthcare Foundation made several statements with which we strongly disagree ("The best way to fight AIDS," @issue).

Global access to HIV/AIDS prevention, testing and antiretroviral treatment is inadequate, and increased funding is needed. We strongly disagree, however, with the suggestion by Khanlou and Weinstein that the best way to fight AIDS is to end government funding for HIV vaccine research and to redirect those funds to prevention, testing and treatment.

History teaches that it is wrong to take an either/or approach to the provision of health care services and vaccine research. In the U.S., despite sustained prevention efforts and widespread use of antiretroviral treatment, 40,000 people are infected with HIV each year. Globally, more than 33 million are infected with HIV. UNAIDS estimates that in 2007, 2.5 million people became infected and 2.1 million deaths occurred from AIDS. Each day, 6,800 persons become infected and 5,700 die from AIDS.

Despite impressive initial steps in antiretroviral rollout in developing countries —- due to the U.S. President's Emergency Plan for AIDS Relief and other programs —- only a fraction of those in need of treatment have received it. The number of HIV-infected persons being treated with antiretroviral drugs in less developed countries is fewer than either the number of deaths or new infections in a single year. Since therapy does not cure HIV, every new infection represents a person who ultimately must be treated for life.

More attention to HIV prevention is urgently needed, and quality education, counseling and testing and other services are warranted. Even when these are fully utilized, it is likely that the number of new infections will remain high.

New and better HIV prevention interventions are clearly required. Historically, vaccines have been the most effective weapons against infectious diseases. The world desperately needs a vaccine for HIV prevention. Khanlou and Weinstein incorrectly stated that there is no precedent for a vaccine against the retroviruses, the viral family to which HIV belongs. Veterinarians administer a vaccine for protection against the leading viral killer of cats, a retrovirus called feline leukemia virus.

Research is a time-consuming process of trial and error, hypothesis generation and testing, refinement and retesting. Vaccine development historically has taken decades, with each interim result contributing new knowledge. The recent clinical trial called the Step Study tested one candidate HIV vaccine. It was disappointing that the vaccine did not protect those who received it. But the study was successful in that it was well-executed and efficiently provided an answer, albeit not the desired one.

History provides powerful lessons. The virus that causes polio was discovered in the 1930s. Initial vaccines tested in the 1930s were ineffective. In the 1940s and early 1950s, summertime polio epidemics caused fear and panic in industrialized countries. Fortunately, vaccine research continued despite initial failures. Progress was based on incremental scientific advances such as the discovery in 1949 by John Enders and his colleagues of how to grow the polio virus in the laboratory. Six years later Jonas Salk's inactivated, injected polio vaccine became available.

By 1957, the number of new polio cases annually had fallen by 90 percent, and over time —- thanks to sustained scientific effort even in the face of early failures —- the iron lung became a museum relic. Imagine if the polio vaccine developers had given up after 20 years, or after a couple of failed vaccine trials.

The National Institutes of Health Summit on HIV Vaccine Research and Development was held in Washington on March 25, led by Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. At this meeting of vaccine and AIDS scientists, care providers and community members, Fauci unequivocally expressed the government's commitment to sustained HIV vaccine research. Based on the input of the summit participants, NIAID will review the balance of resources devoted to HIV/AIDS research and make adjustments to match the state of the science.

Funding for HIV vaccine research must not be cut. If anything, it needs to be increased. Persistence, sustained scientific effort and increased collaboration will drive the quest for an HIV vaccine forward —- just as they did for the polio vaccine.

> Dr. Mark Mulligan is executive director of the Hope Clinic of the Emory Vaccine Center. Dr. James Curran is dean of the Rollins School of Public Health, and co-director of the Center for AIDS Research at Emory University. Eric Hunter is a professor of pathology and laboratory medicine at Emory and co-director of Emory's Center for AIDS Research. Dr. Carlos del Rio is a professor of medicine at Emory and co-director of the university's Center for AIDS Research. Members of the Emory Vaccine Center's Community Advisory Board also contributed to this column: Michael Aycock is a community advocate for AIDS research and prevention, Dr. Barry Baker is a professor of emergency medicine at Emory, Ken Britt is the former chair of AID Atlanta's board of directors, and Dixon Taylor is a community advocate for AIDS research and prevention.