JOHANNESBURG, 1 July 2009 (IRIN) - HIV-positive babies who receive the global standard tuberculosis (TB) vaccine are at high risk of contracting this infectious disease, says a new study in Bulletin, a journal published by the World Health Organisation (WHO).

HIV-positive babies who received the Bacillus Calmette-Guérin (BCG) vaccine were three times more likely to contract TB from the vaccine than previously thought.

Earlier studies documented HIV-positive infants running a risk of contracting TB twice that of their HIV-negative peers as a result of the live cultures in the vaccine, which is fatal to more than 70 percent of all infants infected.

The new findings from research conducted in South Africa could change the vaccine regimens in countries with high rates of HIV and TB; in the meantime, it could save lives, said Dr Simon Schaff of the University of Stellenbosch, one of the report's co-authors.

"There are more complications in HIV-infected infants vaccinated with this BCG strain ... we need to look further into what we can do to prevent the disseminated BCG disease from developing in HIV-infected patients," he told IRIN/PlusNews.

"Doctors should be aware, and should pick it up early. Once you have identified a patient as HIV-positive, and you know that they have received BCG, you can start antiretroviral [medication] early and probably prevent the negative consequences."

A history of concern

There has long been concern regarding the vaccine's risks to HIV-positive babies, which led the WHO Global Advisory Committee on Vaccine Safety to recommend the postponement of BCG vaccinations until a child was six weeks old – which Schaff said put children's lives at risk in countries with a high HIV burden, like South Africa.

The study's authors acknowledged that diagnosing babies with HIV was difficult, with most developing countries only testing infants at six weeks of age, if at all. A blanket postponement of vaccination would only increase the vulnerability of most babies to TB.

BCG still offers HIV-negative babies some measure of protection against TB, the report said, which justified its use until governments could implement selective vaccination based on HIV status. According to UNAIDS, an estimated 420,000 children worldwide receive the BCG vaccination annually.

Schaff stressed that in countries with strong prevention of mother-to-child transmission services, like South Africa, only about five percent of babies born to HIV-positive mothers would be HIV-infected. These infants, though at a greater risk for disseminated BCG, stood about a one percent chance of contracting TB.

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