Disseminated BCGosis in immunocompromised infants: a five-case series in the context of a national BCG vaccination policy change.

backgroundDisseminated Bacillus Calmette-Guérin (BCG) infection (BCGosis) is a rare but serious complication that primarily affects infants with underlying immunodeficiency disorders. In Saudi Arabia, where consanguinity rates are high and primary immunodeficiency disorders are more prevalent, concerns have been raised regarding the safety of routine neonatal BCG vaccination. In 2019, the national immunization schedule was revised to delay BCG vaccination from birth to six months of age.

methodsThis retrospective case series was conducted at a tertiary referral center in Jeddah, Saudi Arabia. Pediatric patients diagnosed with disseminated BCGosis between 2016 and 2023 were identified through electronic medical records. Disseminated BCGosis was defined as systemic infection with involvement of two or more noncontiguous organ systems with microbiological or molecular confirmation of Mycobacterium bovis. Clinical, microbiological, and immunological data were collected and analyzed descriptively.

resultsFive cases of disseminated BCGosis were identified during the study period, all occurring in immunocompromised infants who had received BCG vaccination at birth. Underlying primary immunodeficiency disorders included defects in the IL-12/interferon-gamma pathway and severe combined immunodeficiency. The median age at presentation was approximately 7 months. Clinical manifestations included persistent BCG-site inflammation, lymphadenopathy, and systemic symptoms. The interval from symptom onset to diagnosis ranged from 4 weeks to 7 months, with longer delays observed in cases presenting initially with localized disease. All cases were confirmed microbiologically. One patient died despite treatment, while the remaining patients responded to prolonged anti-tuberculous therapy and adjunctive immunotherapy. No cases of disseminated BCGosis were identified at our institution in the four years following the implementation of delayed BCG vaccination.

conclusionsThis case series describes disseminated BCGosis occurring exclusively in immunocompromised infants vaccinated at birth and not being observed after the implementation of delayed BCG vaccination. Given the observational design and small sample size, these findings should be interpreted with caution. Delaying BCG vaccination may reduce exposure to live vaccination in vulnerable infants without apparent compromise of tuberculosis control. Multicenter studies are needed to validate these observations and inform immunization strategies in high-risk populations.