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The
United Nations has disputed the claim of a US researcher who has challenged widely
held scientific views that most HIV infections in Africa result from dirty medical
needles and other unsafe medical practices rather than unsafe sex.
Dr David Gisselquist, writing in the March issue of the International Journal of STDs and AIDS, estimates that about 60 per cent of people with HIV in Africa could have become infected though contaminated needles rather than through sexual contact. Evidence that supports his contention includes:
UNAIDS, however, says Gisselquist's conclusions are not supported by adequate studies. They put the figure for medical transmission at nearer five per cent. "Unsafe sex continues to be the major route of transmission throughout the world," said Catherine Hankins, UNAIDS' chief scientific adviser. "We're concerned that a report like this might tend to make people drop their guard and not use condoms."
Gisselquist's study also only looked at studies of HIV transmission between 1980 and 1988. This was in the early days of the epidemic: the same findings may not apply since that time. Laurence Gibson
Next issue features an interview with Dr Gisselquist
French scientists claim to have 'reactivated' the immune system of 60 per cent of patients involved in a trial of a new vaccine - temporarily named Alvac - thus providing a defence against HIV.
Patients who received the vaccine in experiments carried out last year were not cured, said Professor Michel Kazatchkine, Director of the National Aids Research Agency. "We cannot use the term 'cure' because it would mean that we have eradicated the virus," he said. "The results are nevertheless extremely encouraging."
Kazatchkine added. "We know that some HIV positive patients can naturally develop immunity to the virus. But our experiments show that the number of people developing these defences rise dramatically with the aid of the vaccine."
Traditional vaccines are used to "prime" a person's immune system before a possible infection. Therapeutic vaccines attempt to "teach" a person's immune system to fight a virus after it has infected them. They could control viral loads over a prolonged period and avoid the need for continuous anti-viral drugs.
In one experiment at La Pitié-Salpêtrière Hospital in Paris, 48 positive patients received four injections of the vaccine at monthly intervals and continued their normal HIV treatment regime.
A month after the last injection of Alvac, the patients stopped their combination therapy. "More than 60 per cent of the patients developed a defence against HIV," says Professor Christine Katlama, who co-ordinated the experiments at La Pitié. "We could wake up the patients' immune system and block reproduction of the virus."
In the second experiment carried out at the Henri-Mondor hospital in Créteil, Paris, half of 70 patients on combination therapy were also given Alvac. After nine months of treatment, 63 of them stopped taking drugs.
A quarter of them developed strong enough immune defences against HIV to give up combination therapy, at least temporarily. Only five per cent of a group not given the vaccine developed similar immune responses.
A
study comparing Trizivir®, GSK's one-twice-a-day HIV pill, with regimes containing
efavirenz has been prematurely halted. Interim figures showed that twice as many
patients on Trizivir failed treatment as those on efavirenz, and also tended to
fail twice as quickly.
Trizivir is a combination of AZT, 3TC and abacavir and as such is the only widely prescribed HIV combination therapy consisting of drugs of only one class - the nucleoside reverse transcriptase inhibitors (NRTIs).
In the ACTG A5095 study, 1,147 patients new to HIV treatment were divided into three groups. One group took Trizivir: one took AZT/3TC/efavirenz and one took Trizivir + efavirenz.
It was found after 32 weeks that 21 per cent of the patients on Trizivir had 'rebounded' to having HIV viral loads over 200, compared with 10 per cent of those taking either efavirenz regime. It was estimated that the average rate of 'rebound' was seven per cent over three months for Trizivir as opposed to 3.5 per cent for efavirenz.
This was not driven by side effects or 'drop outs' as all groups experienced approximately the same level of side effects and the same proportions dropped out.
The US Data and Safety Monitoring Board concluded: "the triple nucleoside regime is demonstrably inferior to the other two". Patients taking Trizivir were unblinded, i.e. told what they were taking: the other two groups remain blinded so that the study can continue with the aim of establishing if the addition of abacavir improves the success of the AZT/3TC/efavirenz regime.
Previous studies have shown a closer match between the performance of Trizivir and other therapies. But the decision to stop a drug trial is only usually taken if regulators are satisfied that such a significant difference in treatments has become apparent that it would be unethical to continue.
The Aids Healthcare Foundation (AHF), a group that provides treatment for people without health insurance in the USA, and also runs two clinics in Africa, criticised GSK for attempting to play down the significance of the trial. AHF President Michael Weinstein commented: "Even after this disappointing announcement, GSK still plans to continue pushing Trizivir despite its lack of efficacy." Gus Cairns
New
nelfinavir