on mother-to-child transmission (MTCT) of HIV. In 1994, a study co-sponsored by NIAID demonstrated that the drug AZT, given to HIV-infected women who had little or no prior antiretroviral therapy (ART), reduced the risk of MTCT by two-thirds. In 1999, an NIAID-funded study in Uganda found that two oral doses of the inexpensive drug nevirapine—one given to HIV-infected mothers at the onset of labor and another to their infants soon after birth—reduced MTCT by half when compared with a similar course of AZT. Subsequent clinical trials, including some funded by NIAID, showed that AIDS drugs also can reduce the risk of MTCT through breast milk. These and other studies have led to World Health Organization recommendations that can help prevent MTCT while allowing women in resource-limited settings to breastfeed their infants safely. More recently, NIAID-funded scientists found that testing at-risk infants for HIV and then giving ART immediately to those who test positive dramatically reduces rates of illness and death. HIV-infected infants were four times less likely to die if given ART immediately after they were diagnosed with HIV, when compared with the standard of care (beginning ART in infants when they showed signs of HIV illness or a weakened immune system). This finding helped influence the World Health Organization (WHO) to change its guidelines for treating HIV-infected infants. The guidelines now strongly recommend starting ART in all children under age 2 immediately after they have been diagnosed with HIV, regardless of their health status. Clinical training programs NIAID offers three-year fellowships for medical trainees in allergy/immunology and infectious diseases. These Accreditation Council for Graduate Medical Education (ACGME)-accredited fellowships provide intensive clinical training and research mentorship in clinical and basic science laboratories. Both NIAID fellowship training programs include one full year of clinical responsibilities including two or three months of the first year caring for patients at the NIH Clinical Center, the nation's largest hospital devoted to clinical research. The subsequent two years are dedicated to research. Allergy and immunology The Allergy and Immunology Clinical Fellowship Program is open to physicians who are on track to complete an approved internal medicine or pediatric medicine residency program. Fellows are eligible to sit for the Board of Allergy and Immunology certification examination after two years. Kelly Stone is the director of the fellowship training program. Infectious diseases The Infectious Diseases Fellowship Program is open to physicians who have completed three years of