AIDS vaccine may have increased infection rate

[Guest guest]

AIDS vaccine may have raised risk of infection

By Craig Timberg

The Washington Post

JOHANNESBURG, South Africa — South African AIDS researchers have

begun warning hundreds of volunteers that a highly touted

experimental vaccine they received in recent months might make them

more, not less, likely to contract HIV in the midst of one of the

world's most rampant epidemics.

The move stems from the discovery last month that an AIDS vaccine

developed by Merck & Co. might have led to more infections than it

averted among study subjects in the United States and other

countries. Among those who received at least two doses of the

vaccine, 19 contracted HIV, compared with 11 of those given placebos.

Researchers shut down the trial on the grounds that the vaccine was

proving ineffective, but the surge in infection among vaccinated

volunteers prompted intense scientific debate and anxiety among

researchers. The failure of the Merck vaccine is the latest in a

series of disappointing results for research projects aimed at

curbing AIDS.

" This is my worst nightmare, " said Glenda Gray, the lead South Africa

investigator for the vaccine study. " I haven't slept for days. I have

a headache. I'm ready to resign from trials for the rest of my life. "

Researchers in Soweto, Cape Town, Durban and two other sites began

contacting South Africa's 801 trial participants on Tuesday, mainly

by cellphone text message. The goal is to tell each one individually

whether he or she had received a placebo or the vaccine, a process

called " unblinding " the trial. Researchers are telling the roughly

half who received the vaccine that it might have increased their risk

of contracting HIV.

" It's quite shocking, " said Nelly Nonoise, 26, who had received three

injections of the vaccine in her left shoulder.

She added, " I probably wouldn't have joined the study knowing there's

a risk. "

Merck developed the vaccine in conjunction with the U.S. National

Institutes of Health, and until September's announcement, researchers

worldwide considered it the most promising candidate yet in a

multibillion-dollar quest for an AIDS vaccine dating to the 1980s.

Scientists crafted the vaccine by genetically altering a common virus

to include elements of HIV.

They hoped that it would trigger an immune response that would make

recipients less likely to contract HIV, or at least delay the onset

of full-blown AIDS.

The vaccine could not have caused infection, researchers say, but it

could have caused immunological changes that made it easier for the

virus to take hold during a later exposure.

The Merck vaccine trials took place in 15 cities in the United

States, including Boston, Los Angeles and New York, and three in

Canada. There also were sites in Peru, Brazil, Australia, Haiti, the

Dominican Republic and Jamaica. Those trials began in December 2004

and included 3,000 participants, mostly gay men.

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In South Africa — where an estimated 5.5 million people are infected

with HIV, more than in any other country — the study used the same

vaccine but was administered separately. The trial here started

later, with the first injections this year, and had its own ethics

oversight board. Most of the subjects were heterosexual.

The ethics oversight board in the United States, which monitored the

trial everywhere but in South Africa, has not decided whether to tell

participants if they received the placebo or the vaccine, said Mark

Feinberg, vice president for medical affairs and policy for Merck.

Continuing research could be compromised, he said, if participants

were told immediately whether they received the placebo or the

vaccine. Vaccine researchers are scheduled to meet in Seattle on Nov. 7.

Meryl Nass, MD

Mount Desert Island Hospital

Bar Harbor, Maine 04609

207 288-5081 ext. 220

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