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The polymorphism of the HLA system has been extensively studied in COVID‐19 infection, however there are no data about the role of HLA on vaccine response. We report here the HLA‐A, ‐B, ‐C, and DRB1 allelic frequencies of n = 111 individuals after BNT162b2 mRNA vaccine, selected on the basis of lower antibody levels (<5% percentile) after the second dose among a total of n = 2569 vaccinees, and compare them with the frequencies of a reference population. We found that differences in the frequencies of the alleles HLA‐A*03:01, A*33:03, B*58:01 and at least one haplotype (HLA‐A*24:02~C*07:01~B*18:01~DRB1*11:04) are associated with a weaker antibody response after vaccination, together with the age of vaccinees. Our results might suggest a role played by some HLA alleles or haplotypes in antibody production after the BNT162b2 mRNA vaccine, giving insights into the tracking of potentially susceptible individuals across populations. Further studies are needed to better define our exploratory findings and dissect the role of HLA polymorphism on response to anti‐COVID‐19 vaccines. [ABSTRACT FROM AUTHOR]

Marktel S, Napolitano S, Zino E, Cappelli B, Chiesa R, Poli F, Crocchiolo R, Ronchi P, Rossini S, Ciceri F, Roncarolo MG, Fleischhauer K. Platelet transfusion refractoriness in highly immunized beta thalassemia children undergoing stem cell transplantation. Pediatr Transplantation 2010: 14:393–401. © 2010 John Wiley & Sons A/S. Immune-mediated refractoriness to platelet transfusion is a major problem in patients undergoing HSCT. In a cohort of 50 pediatric patients affected by beta thalassemia coming from Middle East countries, we experienced a high incidence of refractoriness because of anti-HLA antibodies during post-HSCT aplasia. In a risk factors analysis, factors predicting a negative transfusion outcome were presence of spleen and the number of anti-HLA antibodies. We adopted a policy to select platelet donors by avoiding HLA antigens against which the patient had specific antibodies. Transfusion of dedicated units resulted in 26% refractoriness compared to 74% to random units (p < 0.0001). When dedicated transfusions were used, the presence of spleen did not influence transfusion outcome. Analyzing transfusion outcome depending on the degree of HLA match and ABO compatibility, 76% successful transfusions were obtained with HLA-matched- ABO compatible followed by 67% in HLA-1mismatch- ABO compatible or HLA-matched- ABO incompatible and by 46% in HLA-1mismatch- ABO incompatible. In conclusion, we provide evidence that the selection of platelet donors according to patient characteristics, anti-HLA antibodies and ABO matching, is successful in reducing platelet refractoriness in heavily alloimmunized thalassemia patients undergoing transplantation. [ABSTRACT FROM AUTHOR]