A cluster of pediatric vaccine-induced immune thrombotic thrombocytopenia–like cases with thrombosis and thrombocytopenia following respiratory infections—case series

Background

Adenoviral vector COVID-19 vaccine-induced immune thrombotic thrombocytopenia (VITT) is a heparin-independent platelet-activating disorder. An increasing number of VITT-like disorders without previous vaccination are being identified.

Key Clinical Question

To explore the association of the pediatric cluster of postinfectious thrombosis and thrombocytopenia with VITT-like disorders.

Clinical Approach

Three children with severe thrombocytopenia, coagulopathy, elevated D-dimer, and thrombotic events (cerebral venous sinus thrombosis) were reported. Two had positive nasopharyngeal samples for adenovirus, and 1 had group A streptococcus infection. They all had a COVID-19 history and low-risk antiphospholipid syndrome. Heterozygosity for factor V Leiden was found in 2 children. In 2 patients for whom anti–platelet factor 4 (PF4) serology was performed, positive results were found by PF4/polyanion lateral-flow immunoassay but negative results by PF4/polyanion chemiluminescence immunoassay. All patients were treated with enoxaparin or fondaparinux and intravenous immunoglobulin, while 3 received platelets transfusion and steroids.

Conclusion

This cluster of pediatric cases with thrombosis and thrombocytopenia may indicate a postinfectious (most notably, postadenovirus) VITT-like disorder.