Introduction Vaccine‐induced thrombotic thrombocytopenia (VITT) has been reported after vaccination with the adenoviral vector coronavirus disease 2019 (COVID‐19) vaccine ChAdOx1 nCoV‐19 in European countries. To date, two cases of VITT have been reported in Thais after COVID‐19 vaccination. We determined the frequency of anti–platelet factor 4 (PF4)/polyanionic antibodies in the Thai population receiving the COVID‐19 vaccines. Methods We conducted a cross‐sectional study to evaluate the prevalence of anti‐PF4/polyanionic antibodies in health care workers who received COVID‐19 vaccination with ChAdOx1 nCoV‐19 or CoronaVac within 7 to 35 days. A control population who had not been vaccinated was also included. Anti‐PF4/polyanionic antibodies were detected using ELISA. Functional assay with platelet aggregation was performed for all positive anti‐PF4/polyanionic antibody ELISA tests. Results A total of 646 participants were included in the study; 221 received ChAdOx1 nCoV‐19, 232 received CoronaVac, and 193 participants were in the control group. The prevalence of anti‐PF4 antibodies was 2.3% (95% confidence interval [CI], 0.7‐5.2), 1.7% (95% CI, 0.5‐4.4) in the ChAdOx1 nCoV‐19 and CoronaVac groups, respectively. There was no positive test in the control group. None of the PF4/polyanionic positive sera induced platelet aggregation. Conclusion We found a low prevalence of anti‐PF4 antibodies in Thais after vaccination with ChAdOx1 nCoV‐19 and CoronaVac. None of the antibodies were functional and lacked an association with VITT.

Objectives TP53 mutation is found frequently in therapy related acute myeloid leukemia (AML)/ myelodysplastic syndrome (MDS), AML and MDS patients with monosomy or complex karyotype. However, the prevalence and treatment outcome in TP53 mutated AML/MDS patients in Asian population are scarce. We therefore conducted this study to analyze the prevalence and the treatment outcomes of TP53 mutation in AML and MDS-EB patients. Methods Patients with newly diagnosed AML and MDS-EB were recruited, extraction of deoxyribonucleic acid from bone marrow samples were done and then performing TP53 mutation analysis, using MassArray® System (Agena Bioscience, CA, USA). Results A total of 132 AML/MDS patients were recruited, patients with de novo AML, secondary AML, MDS-EB1, MDS-EB2 and T-AML/MDS were seen in 66, 13, 9, 9 and 3%, respectively. TP53 mutation was found in 14 patients (10.6%), and prevalence of TP53 mutation in T-AML/MDS, secondary AML, de novo AML and MDS-EB patients were 50, 17.6, 9.2 and 8%, respectively. Three patients had double heterozygous TP53 mutation. Mutated TP53 was significantly detected in patients with monosomy and complex chromosome. Common TP53 mutation were R290C, T220C, A249S and V31I which V31I mutation was reported only in Taiwanese patients. Most variant allele frequency (VAF) of TP53 mutation in the study were greater than 40%. Three year-overall survival (OS) in the whole population was 22%, 3y-OS in AML and MDS-EB patients were 22 and 27%, respectively. The 1y-OS in patients with TP53-mutant AML/MDS were shorter than that in TP53 wild-type patients, 14% versus 50%, P = 0.001. In multivariate analysis, factors affecting OS in 132 AML/MDS patients was mutant TP53 (P = 0.023, HR = 1.20–7.02), whereas, WBC count> 100,000/μL (P = 0.004, HR = 1.32–4.16) and complex karyotype (P = 0.038, HR = 1.07–9.78) were associated with shorter OS in AML patients. Discussion In this study, the prevalence of TP53 mutation in de novo AML and MDS-EB patients were low but it had impact on survival. Patients with monosomy or complex karyotype had more frequent TP53 mutation.

Objectives: TP53 mutation is found frequently in therapy related acute myeloid leukemia (AML)/ myelodysplastic syndrome (MDS), AML and MDS patients with monosomy or complex karyotype. However, the prevalence and treatment outcome in TP53 mutated AML/MDS patients in Asian population are scarce. We therefore conducted this study to analyze the prevalence and the treatment outcomes of TP53 mutation in AML and MDS-EB patients. Methods: Patients with newly diagnosed AML and MDS-EB were recruited, extraction of deoxyribonucleic acid from bone marrow samples were done and then performing TP53 mutation analysis, using MassArray® System (Agena Bioscience, CA, USA). Results: A total of 132 AML/MDS patients were recruited, patients with de novo AML, secondary AML, MDS-EB1, MDS-EB2 and T-AML/MDS were seen in 66%, 13%, 9%, 9% and 3%, respectively. TP53 mutation was found in 14 patients (10.6%), and prevalence of TP53 mutation in T-AML/MDS, secondary AML, de novo AML and MDS-EB patients were 50%, 17.6%, 9.2% and 8%, respectively. Three patients had double heterozygous TP53 mutation. Mutated TP53 was significantly detected in patients with monosomy and complex chromosome. Common TP53 mutation were R290C, T220C, A249S and V31I which V31I mutation was reported only in Taiwanese patients. Most variant allele frequency (VAF) of TP53 mutation in the study were greater than 40%. Three year-overall survival (OS) in the whole population was 22%, 3y-OS in AML and MDS-EB patients were 22% and 27%, respectively. In multivariate analysis, factors affecting OS in 132 AML/MDS patients was mutant TP53 (P= 0.023, HR= 1.20- 7.02), whereas, WBC count> 100,000/μL (P= 0.004, HR= 1.32- 4.16) and complex karyotype (P= 0.038, HR= 1.07- 9.78) were associated with shorter OS in AML patients. Discussion: In this study, the prevalence of TP53 mutation in de novo AML and MDS-EB patients were low but it had impact on survival. Patients with monosomy or complex karyotype had more frequent TP53 mutation.

Introduction: Vaccine-induced thrombotic thrombocytopenia (VITT) has been reported after vaccination with the adenoviral vector COVID-19 vaccine ChAdOx1 nCoV-19 in European countries. To date, no case of VITT has been reported in Thais after COVID-19 vaccination. We determined the frequency of anti-PF4/polyanionic antibodies in the Thai population receiving the COVID-19 vaccines. Methods: We conducted a cross-sectional study to evaluate the prevalence of anti-PF4/polyanionic antibodies in health care workers who received COVID-19 vaccination with ChAdOx1 nCoV-19 or CoronaVac within 7-35 days. A control population who had not been vaccinated was also included. Anti-PF4/polyanionic antibodies were detected using enzyme-link immunosorbent assay (ELISA). Functional assay with platelet aggregation was performed for all positive anti-PF4/polyanionic antibody ELISA tests. Results: A total of 646 participants were included in the study. 221 received ChAdOx1 nCoV-19, 232 received CoronaVac, and 193 participants were in the control group. The prevalence of anti-PF4 antibodies was 2.3% (95% confidence interval [CI] 0.7 to 5.2), 1.7% (95% CI, 0.5 to 4.4) in the ChAdOx1 nCoV-19 and CoronaVac groups, respectively. There was no positive test in the control group. None of the PF4/polyanionic positive sera induced platelet aggregation. Conclusion: We found a low prevalence of anti-PF4 antibodies in Thais after vaccination with ChAdOx1 nCoV-19 and CoronaVac. Low titer positive PF4/polyanionic ELISA results should be interpreted with caution when screening asymptomatic individuals after vaccination against COVID-19.