BCG vaccination in children with severe combined immunodeficiency in a tertiary center: evaluation of complications and risks.

Objective: To describe the complications and risks associated with BCG (Bacillus Calmette-Guérin) vaccination in patients diagnosed with SCID (Severe Combined Immunodeficiency).

Methods: This is a descriptive case series study. Medical charts were retrospectively reviewed for demographics, clinical manifestation, laboratory findings at diagnosis, outcome, and diagnosis of BCG vaccine-associated complications.

Results: Eleven patients diagnosed with SCID were enrolled. Ten were male. Seven (64 %) were considered probable SCID, while four (36 %) were considered definite SCID (genetically confirmed). The median age at the onset of symptoms was one month; the median age at SCID diagnosis was four months. Respiratory symptoms were the most frequent. Eight patients were vaccinated within seven days of life. Seven (87 %) of these patients experienced BCG vaccine-associated complications (86 % disseminated reactions; 14 % localized reactions). BCG vaccine-associated complications were the first clinical manifestation in 75 % of the vaccinated patients. Less than half of the patients (36 %) underwent hematopoietic stem cell transplantation. The overall death rate was elevated (73 %); the death rate related to BCG vaccination was 25 %.

Conclusions: Patients with SCID can present a high rate of BCG vaccine-associated complications, which negatively impact the clinical outcome and mortality. Pediatricians must be aware that BCG vaccine-associated complications can be the first presentation and a warning sign of SCID. Implementing newborn screening for SCID in Brazil may represent a worthy opportunity to impact the health outcomes of affected infants significantly.