Independent report

Pathogen inactivation technologies for platelets: SaBTO position statement

Published 24 February 2023

SaBTO recommendations

On 24 May 2022, members of the Advisory Committee on the Safety of Blood, Tissues and Organs (SaBTO) met to review the current position on pathogen reduction and inactivation technologies for the safety of platelet concentrates. SaBTO acknowledged that evidence gathered by the Serious Hazards of Transfusion (SHOT) haemovigilance scheme supported the safety of current measures adopted by the UK blood services. All 4 services currently use bacterial screening rather than pathogen inactivation (PI).

SaBTO made the following recommendations:

• no change in SaBTO’s current recommendations for maintaining the safety of platelets
• current recommendations will be reviewed in 3 years or sooner if new relevant information or technologies become available

SaBTO will work with relevant interested parties to develop guidelines for the health economic evaluation of interventions that include consideration of new and emerging infections.

Evidence

In 2014, SaBTO published the report of a working group that reviewed the PI of platelets.

The recommendations included:

The driver to recommend pathogen inactivation for platelets, in the absence of systems for red cells/whole blood, would be to provide enhanced safety with regard to bacterial transmission. Clear evidence of overall clinical benefit, however, is not apparent at this time [2013].

Current bacterial screening, combined with diversion pouches and enhanced skin cleansing, is already providing a high degree of bacterial safety, with no reported case of transfusion-transmitted infection in platelets since 2009.

The limitations of pathogen inactivation with regard to certain strains of pathogenic bacterial species remain to be clarified through further studies.

The estimated increase in demand will increase donor exposure and hence potential risks from complications not reduced by either pathogen inactivation or Platelet Additive Solution.

System benefits, such as removal of irradiation machines and travel deferrals, cannot accrue until there are pathogen inactivation systems suitable for either red cells or whole blood. Under the current circumstances, therefore, the cost-effectiveness of pathogen inactivation remains very low.

For these reasons, implementation of PI of platelets is not currently recommended for the UK Blood Services. The issue should be reviewed again if significant new information becomes available with respect to the issues mentioned above, and/or if costs compared to bacterial screening are significantly reduced.

Since the report in 2014, evidence has continued to accrue on the safety of the current bacterial screening method used by all 4 blood services in the UK. The 2020 annual SHOT report (chapter 21) indicated that:

• in 2020 there were no reported cases of transfusion-transmitted infections (TTI)
• there was one each year for the previous 4 years

While these findings are encouraging, there is no cause for complacency as there will be a real risk of both unrecognised and non-reported cases. Such a risk would be present even if reporting of TTI were mandatory. The international use of bacterial screening of platelets has been recently reviewed (Kamel H and others).

Since the report in 2014, there have also been advances in PI technologies. (For examples, see reviews such as Cid J and Lozano M; Escolar G and others.)

Possible benefits of PI over current methods include protection against some new and emerging transfusion transmissible infections. However, PI has not provided protection against recent infections such as hepatitis E, vCJD, hepatitis A or SARS-CoV-2.

Possible disadvantages of PI include:

• loss of platelet quality and quantity during processing
• costs of implementing PI continues to lie above the threshold for cost-effectiveness

SaBTO recognises that developments in PI might allow such technologies to be used for red cells or whole blood. SaBTO also recognises the possible benefits of PI should susceptible new pathogens and emerging infections become a threat to the safety of platelets, or other components, that cannot be mitigated by screening techniques.

However, SaBTO recognises that the impact of new infections can, at least in part, be mitigated by effective horizon scanning, introduction of effective deferral and the ability to rapidly develop diagnostic techniques such as PCR-based screening tests (as seen in the COVID-19 pandemic). SaBTO recognises that there would be financial and logistic implications of changing to PI which need to be balanced against any benefit.

SaBTO will continue to keep the situation under review.

References

Kamel H, Ramirez-Arcos S, McDonald C; International Society of Blood Transfusion transfusion-transmitted infectious disease bacterial working party bacterial subgroup. ‘The international experience of bacterial screen testing of platelet components with automated microbial detection systems: an update’. Vox Sang. 2022 Feb 17.

Cid J and Lozano M. ‘Pathogen inactivation of platelets for transfusion’. Platelets. 2022 Jan 2;33(1):23 to 26.

Escolar G, Diaz-Ricart M and McCullough J. ‘Impact of different pathogen reduction technologies on the biochemistry, function, and clinical effectiveness of platelet concentrates: an updated view during a pandemic’. Transfusion. 2022 Jan;62(1):227 to 246.