A new three-year study by the World Health Organization (WHO) has shown that babies with HIV could die if given a standard tuberculosis vaccine, The Associated Press reports. The study was published July 1 in the journal Bulletin of the World Health Organization.

According to the study, babies born with HIV in South Africa had a greater risk of contracting a fatal form of TB when given the commonly used BCG vaccine. WHO recommends not vaccinating babies who are living with the virus and delaying vaccination for those whose HIV status is unknown.