【Objective】 To analyze the reasons for the invalidity of blood nucleic acid test results, and to explore the countermeasures to reduce the invalidity of the test. 【Methods】 From 2019 to 2021, the number of tests performed in our laboratory for Cobas s201 blood nucleic acid screening system and the number of batches and tests with invalid results were counted, and the types and reasons of invalid results were analyzed. 【Results】 From 2019 to 2021, the Cobas s201 nucleic acid detection system detected a total of 5, 420 batches and 127, 950 pools, and the invalid rate of batches and pools were 1.83% and 1.97%, respectively. The types of invalid results can be summarized as improper operation, sample quality problems, invalid quality control (IQC), equipment failure and others. Among them, IQC and equipment failure were the main reasons for invalid results, accounting for 44.51% and 39.96%, respectively. IQC was mainly related to cross-contamination of samples and insufficient mixing of quality control products. Equipment failures mostly occurred in the robotic arm gripper of the nucleic acid extraction instrument and the TC module of the amplification instrument. 【Conclusion】 The laboratory should conduct quality monitoring for invalid results, and take targeted improvement measures, especially to reduce invalid results caused by invalid quality control and instrument failure.

Objective To establish a quality control mechanism based on the Poisson distribution for monitoring con-tamination in nucleic acid testing(NAT)laboratories.Methods The study collected NAT single-reactivity rates and dis-criminatory test reactivity rates from the Grifols Panther NAT system from 2022 to 2023.The Poisson distribution probability method was used to calculate the daily probability of nucleic acid single reactivity.Sensitivity and specificity of the quality control model were further validated using single-reactivity rates,discriminatory reactivity rates and ROC curve analysis,fol-lowed by proposing corresponding multi-rule quality control strategies.Results Using P=0.05 as the threshold for out-of-control,the Poisson distribution probability quality control model identified 40 out-of-control points with P<0.05.After man-ual verification using discriminatory reactivity rates,20 out-of-control points were confirmed.The sensitivity of determining out-of-control was 60.0%,and the specificity was 95.6%.Due to the high number of out-of-control points,it is recommen-ded to combine discriminatory reactivity rates and employ multi-rule quality control methods for quality monitoring.Under the multi-rule quality control,there were 18 warning points and 2 out-of-control points for NAT single reactivity from 2022 to 2023.Conclusion The multi-rule NAT single-reactivity monitoring mechanism based on the Poisson distribution probability is more suitable for nucleic acid laboratories to monitor and warn of laboratory contamination,thereby enhancing the manage-ment capabilities and detection quality of nucleic acid laboratories.

【Objective】 To investigate the distribution of ABO and RhD blood groups among voluntary blood donors in Guangzhou, in order to ensure clinical blood safety and better serve blood donors. 【Methods】 Routine ABO and RhD blood group screening tests were carried out among voluntary blood donors from January 2021 to December 2022. The composition ratio of ABO blood group was statistically analyzed. The samples with discrepancy between forward and reverse blood grouping and negative RhD blood group samples were further verified by serological test to analyze the ABO subtypes and the reasons for missed detection. 【Results】 A total of 749 123 blood samples were screened from January 2021 to December 2022, and 513 291 samples were collected after excluding repeat blood donors, with the ABO blood groups as 208 126(40.55%) of O type, 138 859(27.05%) of A type, 130 987(25.52%) of B type and 35 319(6.88%) of AB type. The screening results showed discrepancy between forward and reverse blood grouping in 506 samples, of which 58 were with weak/non-erythrocyte reaction, 16 with erythrocyte reaction, 215 with weak/non-serum reaction, and 217 with serum reaction. Further serological test indicated that 44 samples were ABO subtypes, among which 13 were subtype A, 26 subtype B, 5 subtype AB and 3 B (A) and 14 Bombay-like blood group. The blood group with the highest missed detection rate in repeat blood donors were A3/B3 subtype (68.42%). A total of 128 unexpected antibody positive samples were detected among 513 291 samples A total of 2 277 samples were screened negative for RhD blood type, of which 2 188 were confirmed to be Rh negative (2 188/513 291, 0.43%), 89 were D variants (89/513 291, 0.02%, ) and 30 were detected with unexpected antibodies (30/2 188, 1.37%). 【Conclusion】 The ABO blood group distribution of blood donors in Guangzhou is O>A>B>AB, and the proportion of RhD negative population is 0.43%, slightly highter than 0.3%-0.4% of Han population nationwide. The ABO blood group subtype is dominated by B subtype. The detection rate and missed detection rate of A3/B3 subtypes in routine blood group tests are the highest.

【Objective】 To retrospectively analyze the unqualified blood screening results of voluntary blood donors in Guangzhou area during 2016~2020, and analyze various factors that affect the blood screening results, for the purpose of providing a scientific basis for recruitment and retention of blood donors, improving blood safety, and avoiding waste of blood resources. 【Methods】 A total of 1 548 204 voluntary blood donors in Guangzhou from 2016 to 2020 were selected as the research objects, and the blood samples were screened by dual ELISA and once NAT. The unqualified rate of different years and populations were counted and the analysis of risks of unqualified blood testing was performed by conditional Logistics regression. 【Results】 An overall unqualified rate of blood screening was 2.52% in Guangzhou from 2016 to 2020, the unqualified rate of every year showed a downward trend first and then an upward trend. HBsAg and ALT were the two primary deferral causes, the positive rate was 0.65%(10 129/1 548 204) and 1.22%(18 824/1 548 204), respectively; the unqualified rate in male blood donors3.10%(31 091/1 004 079) was significantly higher than that in female(P<0.05), and that in blood donors aged 18~25 was 1.84%(12 781/694 374), which was lower than the other three age groups (P<0.05). Fewer students(1.33%, 4 024/302 007) and bachelor degree donors(1.57%, 5 379/341 662) were deferred. Compared with individual blood donors, group blood donors’ deferral rate(2.62%, 21 307/813 664) was higher. The deferral rate of first-time blood donors(4.57%, 24 469/535 551) were higher than the repeated blood donors (P<0.05) , meanwhile, whole blood donors(2.84%, 38 111/1 340 678) higher than those apheresis donors (P<0.05). Gender, age, occupation, education, frequency and blood components donated were risk factors for unqualified blood screening. 【Conclusion】 The deferral rates of voluntary blood donors in Guangzhou showed an overall upward trend, from 2016 to 2022. HBsAg and ALT were the primary deferral causes, and there were differences in demographics and blood donation characteristics. To formulate targeted recruitment strategies according to the test results of voluntary blood donors, and strengthen the publicity of low-risk groups and the consultation and screening before blood donation, will be a great benefit for reducing the blood scrap and guaranteeing the blood safety.

【Objective】 To assess the trend of hepatitis B virus (HBV) prevalence and associated risk factors among voluntary blood donors in Guangzhou area from 2011 to 2020, and to explore the impact of hepatitis B vaccination in neonates on the risk of HBV infection. 【Methods】 Blood samples of 2 624 434 voluntary blood donors from 2011 to 2020 in Guangzhou were tested by HBV surface antigen (HBsAg) enzyme-linked immunosorbent assay (ELISA) reagents twice and nucleic acid test (NAT) reagent once. Samples reactive to ELISA twice, or ELISA once + NAT were considered as HBV infection. The gender, age, ethnicity and region of HBV infected blood donors were collected, and the incidence of HBV infection in blood donors born before and after 1992 (when HBV vaccination was conducted in neonates) was compared. The trend and risk factors of HBV infection in blood donors in Guangzhou from 2011 to 2020 were analyzed. 【Results】 An overall HBV prevalence of 0.75% was found in voluntary blood donors in Guangzhou area from 2010 to 2020, showing an overall downward trend(P<0.05). HBV prevalence was lower in blood donors born after 1992 (0.49 %, 4 825/98 5362) than prior to 1992 (P<0.05). HBV prevalence in male blood donors (0.89%, 15 049/1 695 062) was significantly higher than that in female blood donors (P<0.05). HBV prevalence in blood donors aged 18~25(0.52%, 6 337/1 219 282)was lower than that in other age groups (P<0.05). HBV prevalence was similar in donors resident in Guangdong and other provinces(P>0.05), but both were significantly higher than that in Hong Kong, Macao, Taiwan and foreign countries (P<0.05). HBV prevalence in Han nationality donors was significantly higher than the ethnic minority donors (P<0.05). Gender, age, ethnicity and birth vaccination are the main risk factors for HBV infection among blood donors. 【Conclusion】 The overall HBV prevalence among voluntary blood donors in Guangzhou area from 2011 to 2020 has shown a decreasing trend, and differences have been found in gender, age, region, ethnicity and birth vaccination, which is helpful to formulate targeted recruitment strategies, thus reducing the risk of transfusion transmitted HBV.

【Objective】 To explore the correlation between serological screening of human T-lymphotropic virus antibodies (anti HTLV) and Western blot(WB) confirmatory tests among blood donors, so as to explore the infection status of HTLV Ⅰ/Ⅱ in Guangzhou. 【Methods】 The anti HTLV Ⅰ/Ⅱ enzyme-linked immunosorbent assay(ELISA) kit was used to screen voluntary blood donors from Guangzhou Blood Center from July 2016 to August 2022. WB was used to confirm 395 reactive blood samples by ELISA. The correlation between the S/CO values of anti HTLV Ⅰ/Ⅱ ELISA reagents and the confirmatory test was analyzed using ROC curves. 【Results】 The results showed that 25 out of 395 initially screened reactive blood donor samples were confirmed as HTLV positive by WB, while 16 were uncertain. ROC curve analysis showed a correlation between the S/CO values by ELISA and the confirmatory test results: the S/CO value at the highest Youden index was 3.789, which was the optimal threshold. The S/CO value had a certain correlation with the predicted positive rate of confirmatory results (P<0.05): the larger the S/CO value, the higher the predicted positive value. The overall prevalence of HTLV in Guangzhou is relatively low. 【Conclusion】 The prevalence of HTLV among blood donors in Guangzhou is low.Since the false positive rate of HTLV Ⅰ/Ⅱ antibody by ELISA serological screening is high, the confirmatory testing is particularly important.

【Objective】 To investigate the population data of human immunodeficiency virus (HIV) infections among voluntary blood donors in Guangzhou between 2012 and 2022, and analyze its characteristics and trends, so as to provide valuable data for formulating targeted prevention and ensuring blood safety. 【Methods】 Voluntary blood donors samples from 2012 to 2022 were screened for p24 antigen and anti-HIV by two ELISA diagnostic kits and HIV RNA by nucleic acid test(NAT). The reactive blood samples were sent to the Disease Control and Prevention Center of Guangzhou for anti-HIV confirmatory test by Western blot. The population characteristics of blood donors with confirmed-positive HIV were subsequently analyzed. 【Results】 There were a total of 3 351 596 blood samples from voluntary blood donors in Guangzhou from 2012 to 2022, of which 708 samples were confirmed-positive of anti-HIV, with a total positive rate of 21.12/100 000, showing a decreasing trend (P<0.05). 1) The positive rates of age groups from high to low were 25-34 year old group, 35-44 year old group, 18-24 year old group, and≥45 year old group. The differences among various groups are statistically significant; 2) The anti-HIV positive rate of first-time blood donors (39.23/100 000) was significantly higher than that of repeat blood donors (10.78/100 000) (P<0.05); 3) The anti-HIV positive rate of male blood donors was 30.45/100 000, which was significantly higher than that of female blood donors (3.46/100 000); 4) The anti-HIV positive rate of individual blood donors (32.18/100 000) was higher than that of group blood donors (9.10/100 000) (P<0.05). 【Conclusion】 From 2012 to 2022, the confirmed-positive rate of anti-HIV among voluntary blood donors in Guangzhou showed a downward trend, which was significantly correlated with the implementation of voluntary blood donation and AIDS prevention policies. Young blood donors are of high risk of HIV, and it is necessary to enhance publicity and education on AIDS prevention through multiple channels among young population. Given that the anti-HIV positive rate of first-time blood donors is much higher than that of repeat blood donors, it is recommended to further optimize the health consultation and physical examination process before blood donation, and take multiple measures to screen high-risk behavior groups. Besides, more efforts should be made to promote publicity and education on AIDS prevention among regular blood donors. It is also important to recruit blood donors from low-risk groups and inform the donors about confidential unit exclusion.

【Objective】 To establish and verify a new nucleic acid extraction method for OBI detection with large volume and high sensitivity, and apply it in the quantitative determination of OBI samples with low viral load. 【Methods】 The method for nucleic acid extraction with large volume was established based on the method of Roche nucleic acid detection kit. HBV standards were configured into 10 000 IU/mL, 1 000 IU/mL, 100 IU/mL, 10 IU/mL and 1 IU/mL respectively, and nucleic acid was extracted from the 10 mL standards by magnetic beads. CT values of each concentration were detected by fluorescence quantitative PCR and each concentration gradient was detected in parallel duplicates. The logarithm of virus concentration was taken as the X-axis and the average CT values of two tests were taken as the Y-axis to construct the fluorescence quantitative standard curve and regression equation. Three repeated experiments were conducted to verify the stability of the method. This method was used to extract nucleic acid from OBI samples with low viral load, and fluorescence quantification was performed. 【Results】 The amplification efficiency of fluorescence quantitative standard curves ranged from 90% to 105%, and the regression equation was greater than 0.99. The variation coefficients of variation of CT values were 0.63%, 0.78%, 1.52%, 1.36% and 0.78%, respectively. This method can extract nucleic acid from OBI samples with viral load of 1 IU/mL for quantification. 【Conclusion】 The detection limit of HBV nucleic acid quantitative detection system can reach 1 IU/mL, and it has strong stability and high sensitivity, which can be used for the quantitative detection of OBI with low viral load.