RESUMO
【Objective】 To analyze testing ability of blood testing laboratories in domestic blood establishments, and to comprehensively understand the resource allocation, workload and unqualified blood samples. 【Methods】 All blood testing laboratories reported the quarterly quality indicator data via their EQA system on the website of National Center for Clinical Laboratories (https: //srv.clinet.cn/qblood/report/add1.aspx). We collected related quality indicators throughout 2020, including resource indicators, number of sample detection, and number (rate) of unqualified samples. All the data were integrated by EQA system. 【Results】 1) Throughout 2020, 324 blood testing laboratories reported that 13 529 778 donations were tested by immunoassays and 13 892 927 donations were tested by nucleic acid testing(NAT). Among them, 253 laboratories reported the data correctly throughout four quarters, and they tested 12 015 407 donations. 2) The number of equipment varied greatly among different laboratories, and a certain equipment was often overloaded in some laboratories. 3) The proportion of domestic ELISA reagents was 100% (322/322), while the proportion of imported NAT reagents was 75.33% (220/300). 4) The positive rate of HBsAg was closely related to geographical locations, as Sichuan (0.86%, 5 895/689 445), Guangdong (0.57%, 5 147/895 929), and Guangxi (0.53%, 3 021/573 216) provinces demonstrated higher positive rates than that of other provincial regions. 【Conclusions】 There are many blood stations across China, with great differences in scale and equipment. There are obvious differences in the positive rates of infectious indicators in different regions. Therefore, the laboratory should make horizontal comparison with the laboratories in the same region, to improve the detection quality of the laboratory in time and effectively.
RESUMO
Objective:To evaluate the impact of sample pooling strategy on 2019-nCoV RNA detection results.Methods:Ten negative swabs were stored in 6 ml virus transport medium, mixed thoroughly and diluted 1∶2 and 1∶10. Inactivated 2019-nCoV culture medium was added to simulate pooling samples: 10 pooling samples, 5 pooling samples and 1 swab sample. Extraction and amplification were made using three nucleic acid extraction reagents a, b, and c with different extraction methods and systems, as well as five 2019-nCoV detection reagents A-E with various template loading volumes and sensitivities respectively.Results:For the same sample, the Ct values of extracted templates a were 2.10±0.47 and 3.46±0.62 earlier than extracted templates b and c. For samples with identical amplifying, the Ct valves of N and ORF1ab gene of A reagent were 1.16±0.48 and 2.36±0.54 earlier than that of reagent B. Adding nucleic acid of 10 negative swabs to the amplification system lagged the Ct values of reagent A by about 1.36±0.32 Ct, while Ct values of reagent B were not affected. Extracted by regent a, a lag of 1.66±0.39 Ct on average was observed in C, D, and E reagents in detecting pooling samples of ten swabs as compared with one swab sample. When extracting 400 copies/ml pooling samples of ten swabs by reagent a, N gene could be detected by reagents C and E, but not by reagent D.Conclusion:Large amount of extraneous DNA is introduced by sample pooling, which could interfere the effiency of extraction and amplification. Strategies of using extraction reagents with large loading volume and high effiency, together with amplification reagents with large template volume and low limit of detection are helpful for ensuring detection sensitivity of pooling samples, and greatly reducing the risk of false negative results.