Objective To prepare and evaluate the reference materials for plasma von Willebrand Factor antigen testing with fresh frozen plasma.Methods The candidates were prepared by low temperature centrifugation in 5 different concentration levels.The homogeneity and stability of the preparation was evaluated according to the ISO Guide35 and CNAS-GL03.The comparability between STAGO and IL system was evaluated according to the WS/T 356-2011.Then the preparations were characterized by six laboratories with the Secondary Coagulation Standard established by NIBSC(SSCLOT4).Results Homogeneity evaluation of the preparation showed that there was no statistically significant difference between the groups (P >0.05),the F values of factor analysis of variance were 0.317~0.844,the uncertainty range was 1.01% ~2.06%.A linear regression based on stability evaluation indicated that the linear trend (within 24 weeks)was insignificant (P >0.05). The uncertainty range of long-term (within 24 weeks)stability was 0.79% ~ 1.20%.The results of the preparations on STAGO and IL system were comparable.The certificated values of the candidates were range from 12.2% to 138.9% with uncertainties were 0.06%~0.09%,respectively.The range of combined standard uncertainty was 0.03% ~ 0.16% while the expanded uncertainty was 2.2%~6.7%.Conclusion The reference materials for von Willebrand Factor antigen testing were stable and homogenous with comparability between STAGO and IL.The method of characterization was accurate and reliable.

Currently, human immunodeficiency virus (HIV) surveillance mainly relies on sentinel surveillance and the HIV/acquired immunodeficiency syndrome (AIDS) case reporting system to calculate the HIV infection rate, the number of newly reported HIV cases, and the HIV-related mortality rate, while theses measures are not able to directly estimate the HIV incidence. National-level research is conducted to investigate the characteristics of drug-resistant strains of HIV. HIV infection has the characteristics of a covert progression and a long-term latent phase, making it difficult to identify individuals in the acute infection stage. Conventional monitoring method struggles to determine the infection time of individuals, thereby introducing potential biases in the estimation of the incidence and impacting the comprehensive exploration of disease risk factors and the assessment of intervention measures. Recently, test for recent infection (TRI), as one of AIDS epidemic surveillance and intervention assessment measures, has become a vital way to estimate HIV incidence by testing the cross-sectional specimens. TRI can identify recent HIV infection and long-term HIV infection, consisting of serological and molecular method. Serological assays have been widely used because of their low cost, high accuracy of HIV infection incidence estimate and long development history, and their accuracy and simplicity have achieved significant progress in recent years. According to introduct the principle, accuracy and application of TRI, this paper reviews the latest progress, advantages, and limitations of TRI.