Interpretation of pathogen load in relationship to infectivity and pathogen reduction efficacy

Inactivation of three emerging viruses – severe acute respiratory syndrome coronavirus, Crimean–Congo haemorrhagic fever virus and Nipah virus – in platelet concentrates by ultraviolet C light and in plasma by methylene blue plus visible light

“…If one or more of these viruses is transfusion transmissible, its threshold concentration to elicit disease must be examined to determine whether the capacity of these pathogen inactivation technologies to inactivate the respective virus in plasma and PCs is sufficient to prevent transfusion transmission. Interpreting pathogen load in relationship to infectivity and inactivation efficacy is generally a very complex task . When attempting to do so, it is important to consider that because quantitative polymerase chain reaction (qPCR), the most commonly used approach, measures viral load by detecting a small fragment of the viral genome, the results may not reflect infectivity and that qPCR usually overestimates the titre of circulating infectious agents .…”

“…Interpreting pathogen load in relationship to infectivity and inactivation efficacy is generally a very complex task . When attempting to do so, it is important to consider that because quantitative polymerase chain reaction (qPCR), the most commonly used approach, measures viral load by detecting a small fragment of the viral genome, the results may not reflect infectivity and that qPCR usually overestimates the titre of circulating infectious agents . In contrast, infectivity assays, which were used in this and previous studies , determine the inactivation capacity of a pathogen inactivation method based on intact, functional viral units.…”

The long and winding road to pathogen reduction of platelets, red blood cells and whole blood

“…The latter studies provided the necessary background for the implementation of some observational studies and of 10 randomised clinical trials (RCTs) aimed at the comparison of PRT versus standard platelets in haematology patients. Table II shows in chronological order the sample size, the post-transfusion platelet count increments and the number of patients developing bleeding episodes in the 7 RCTs using the Intercept system (van Rhenen et al, 2003: McCullough et al, 2004Janetzko et al, 2005;Snyder et al, 2005;Kerkhoffs et al, 2010;Lozano et al, 2011;Rebulla et al, 2017;Garban et al, 2018) and in the 3 RCTs using the Mirasol system (Mirasol Clinical Evaluation Study Group, 2010;Rebulla et al, 2017;van der Meer et al, 2018).…”

Concerning the efficacy of pathogen inactivation

“…In this issue of TRANSFUSION, McCullough and colleagues reviewed data relating to pathogen inactivation . They concluded that there was little or no standardization of measurements of the circulating levels of infectious agents and the likelihood of infectivity from these levels, and that there were numerous factors that made it impossible to predict the clinical efficacy of pathogen inactivation technology.…”

“…In this issue of TRANSFUSION, McCullough and colleagues reviewed data relating to pathogen inactivation. 1 They concluded that there was little or no standardization of measurements of the circulating levels of infectious agents and the likelihood of infectivity from these levels, and that there were numerous factors that made it impossible to predict the clinical efficacy of pathogen inactivation technology. They concluded that it was most appropriate to use pathogen inactivation as a supplement to existing testing methods to remove the risk of infection from donations with low levels of agents not detectable by testing.…”