NAIROBI, 14 June 2010 (PlusNews) - Unintended pregnancies during East African clinical trials of an HIV vaccine are proving problematic. "One or two women dropping out of a study of 40 people makes a big difference to the data," said Prof Omu Anzala, programme director of the Kenya AIDS Vaccine Initiative (KAVI).

"One of the conditions for recruitment in these trials is that women must not be pregnant at the time of recruitment, and must not become pregnant for the duration of the trial. Most of the HIV vaccine trials we do in Kenya are phase one trials and the sample size is generally small." A study by KAVI on the issue was recently published in the East African Medical Journal.

Men and women enrolling in such trials usually receive counselling on what to expect, but women are given additional one-on-one counselling on contraception and offered various options, including sexual abstinence.

The KAVI study found that only 39 of the 163 participants in its four clinical HIV vaccine trials since 2001 were women; four of them - who all chose abstinence as their preferred method of contraception - fell pregnant, but all reported being coerced into having unprotected sex by their partners. As a result, Anzala said KAVI would no longer accept abstinence as an option for contraception.

Unwilling to participate

Anzala noted that globally more than half the people infected with HIV were women, but they were under-represented in HIV vaccine trials, and one of the main reasons for their reluctance to participate was the strict contraceptive requirements.

In a 2009 Ugandan study, the requirement to delay pregnancy reduced women's motivation to participate in HIV vaccine trials from 97 percent to 23 percent.

Another 2009 study covering Kenya, Tanzania and Uganda found that women participating in a vaccine trial often used hormonal contraceptives, but incorrect usage had led to unwanted pregnancies. The study recommended that participants more regular and intensive counselling about the proper use of contraceptive technologies.

The ethics of excluding pregnant women

However, according to "The Second Wave: Ending the knowledge gap on treating illness in pregnant women" an article by the Kennedy Institute of Ethics in Georgetown, US, screening pregnant women out of trials meant there was a lack of knowledge about how their bodies processed drugs, compromising the quality of medical care available to them.

"It is unfair and irresponsible to continue a system that compels physicians to use therapeutic agents in an uncontrolled experimental situation virtually every time they prescribe for pregnant women, and for women, and the foetuses they carry, to shoulder those risks when pregnancy is complicated by illness," the authors commented.

A recent article in the scientific magazine, Nature, also made the case that excluding pregnant women from clinical trials was both unethical and unscientific.

In its document on ethical considerations for HIV prevention trials, UNAIDS recommends that pregnant and breast-feeding women be informed about any potential risks to their foetus or child, and that they then be treated as autonomous decision-makers capable of making their own choices.

"Researchers and trial sponsors should include women in clinical trials in order to verify safety and efficacy from their standpoint," the document suggests. "Women ... including those who are sexually active and may become pregnant, be pregnant or be breastfeeding, should be recipients of future safe and effective biomedical HIV prevention interventions."