[Relationship between coronavirus disease 2019 vaccination and the risk of immune thrombocytopenia].

Objectives: To study the relationship between coronavirus disease 2019 (COVID-19) vaccination and the risk of immune thrombocytopenia (ITP).

Methods: A retrospective analysis was conducted on children aged 3-17 years with newly diagnosed ITP who were hospitalized in Children's Hospital Affiliated to Zhengzhou University from November 2021 to December 2022. Clinical data and COVID-19 vaccination status were compared among three groups: ITP patients vaccinated within 12 weeks before onset, vaccinated more than 12 weeks before onset, and unvaccinated. Changes in serum immunoglobulin and complement levels were analyzed among five groups: ITP patients vaccinated <4 weeks before onset, 4-<8 weeks before onset, 8-<12 weeks before onset, ≥12 weeks before onset, and unvaccinated. A case-control design was used to estimate the risk of ITP: 387 children aged 3-17 years with fractures hospitalized during the same period in the emergency department of the hospital were selected as the control group, and the exposure to COVID-19 vaccination within 12, 8, and 4 weeks before onset in ITP children was compared to estimate the risk of ITP.

Results: Among 129 ITP children, there were no statistically significant differences in age, gender, rate of preceding infections, absolute platelet count at initial diagnosis, absolute lymphocyte count at initial diagnosis, bleeding score, positive anti-nuclear antibody rate, absolute platelet count after 4 days of treatment, recurrence rate, and proportion of patients with disease duration ≥3 months among the three groups vaccinated within 12 weeks before onset, vaccinated more than 12 weeks before onset, and unvaccinated (>0.05). There was a statistically significant difference in serum immunoglobulin G, immunoglobulin A, and complement component 3 levels among the groups vaccinated <4 weeks, 4-<8 weeks, 8-<12 weeks, and ≥12 weeks before onset, and unvaccinated (<0.05). The risk estimation results showed that COVID-19 vaccination within 12 weeks, 8 weeks, and 4 weeks before onset did not increase the risk of ITP (>0.05).

Conclusions: COVID-19 vaccination does not increase the risk of ITP.