PB0266 - Effect of COVID-19 Vaccine or Infection on Pediatric Patients with Current or Prior Immune Thrombocytopenia

Background: Exacerbations of Immune Thrombocytopenia (ITP) following COVID-19 infection and vaccination in adults have been observed and examined in detail, but similar studies are lacking in the pediatric population.

Aims: This study aims to investigate the effect of COVID-19 vaccination or infection in pediatric patients with current or previous ITP.

Methods: A single-center retrospective study involving record reviews of 50 pediatric patients with current or previous ITP diagnosed from 2002 to 2022 and who received COVID vaccines or who were infected with COVID was conducted. Possible factors associated with ITP exacerbation were identified and analyzed using descriptive statistics, Fisher's exact test and Independent sample T-tests.

Results: Out of 41 patients who received COVID-19 vaccinations, 12.2% (n=5) developed an ITP exacerbation (defined as >50% decline in platelet counts from baseline or nadir platelet count < 30 x109/L with >20% decrease from baseline or increase in bleeding manifestations noted during post-vaccination follow-up). Risk factors for ITP exacerbation post-COVID vaccination were lower baseline platelet count (p=0.0045) and shorter duration of ITP prior to vaccination (p=0.0475). Out of 9 patients who contracted COVID-19 infection, 2 had prior vaccinations and only 1 unvaccinated patient had an exacerbation. Another patient had a significant drop in platelet count from 151 to 82 on Day 1 of infection.

Conclusion(s): Our findings highlight the potential for ITP exacerbation following COVID-19 vaccination or infection in pediatric ITP patients. More frequent monitoring with platelet counts can be considered in these patients. Moving forward, larger scale studies can be undertaken to study platelet trends in pediatric ITP following COVID-19 infection or vaccination.