Delayed presentations of severe combined immunodeficiency during the SARS‑CoV‑2 pandemic

Background and Aims Severe combined immunodeficiency (SCID) is characterized by severe T lymphocyte dysfunction and variable B/NK cell abnormalities. With extreme susceptibility for infection, SCID usually evolves fatal in the first months in the absence of treatment.. For multiple infectious diseases, epidemiological dynamics were altered during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. Methods We describe two SCID patients with delayed onset of symptoms during the SARS-CoV-2 pandemic. Results P1, a boy, presents with first symptoms of respiratory tract infection at age of 14 months. P2, another boy, presented lower respiratory tract infection and gastroenteritis at 8 months. Previously, both patients had remained free from severe infections, failure-to-thrive or developmental delay. Daycare attendance was postponed because of lockdown measures. Absent thymic shadows prompted further investigations in both instances. Lymphopenia with a T-B+NK+ (P1) and T-B-NK+ (P2) phenotype was found. Pulmonary infection with vaccine-strain measles and parainfluenza (P1) and disseminated adenovirus infection (P2) was documented. Despite broad antimicrobial treatment (including ribavirin (P1) and cidofovir (P2)) respiratory disease progressed. Cardiogenic shock (P1) and hemophagocytic syndrome (P2) developed. Ultimately, multiple organ failure resulted in fatal outcome in both. Genetic testing revealed a homozygous c150_153del in IL7R (P1) and compound heterozygous c.442dupG and c.241C>T in DCLRE1C (P2). Conclusions We describe two patients with SCID, yet late presentation. Their exposure to infection could have been diminished because of reduced microbial transmission during the pandemic. Clinicians should be aware of delayed presentations of severe immune disorders during a global sanitary crisis.