There is an urgent unmet need for short-term interventions to prevent infection in infants exposed to HIV-1 at birth, who have higher mortality rates than infants infected at an older age. Although passively administered antibodies disperse into tissues more slowly than antiretroviral drugs (ART), potent broadly neutralizing monoclonal antibodies (bNAbs) are an attractive approach for post-exposure prophylaxis because of their longer half-life, good safety profile, and the potential for opsonization and Fc-mediated killing of infected cells.