SI26
Interactive Modelling of the Impact a Flu Pandemic may have on Blood Supplies (on behalf of the NHSBT Emergency Planning Group)

Abstract

Introduction The NHS Blood and Transplant (NHSBT) has developed emergency plans based on a few scenarios including a potential Human Flu Pandemic. A model has been created illustrating the impact on the national red cell and platelet stocks using current assumptions made by the NHSBT Emergency Planning Group, NHS and the Department of Health (DH). Methodology As no suitable model was available a model was created in Microsoft Excel, which is widely available within the National Blood Service (NBS) and NHSBT. This allows the user to change planning assumptions which will automatically recalculate the impact on the total NBS stock of red cells and platelets. The model can be used to view different scenarios, e.g. Changes to demand (–10%) Clinical attack rate–the % of total population contracting Flu (25%) Possible duration and profile of pandemic wave as per NHS Flu Contingency Plan % of population caring for victims (5%) Deferral period for donors contracting flu (2 weeks ill and 2 weeks deferred) Whole Blood and component donation supply (increased pre‐pandemic only) Buffy Coat (BC) production (49%) Starting stock (Red Cells 56 k, Platelets 958 doses) % of population self deferring (based on NHSBT figures). Results The activities modelled in this particular scenario would increase red cell stock from 56 k to 62 k before the virus is isolated in the UK. Once there was widespread activity across the UK, red cell stock would fall to 40 k before recovering after the pandemic ends. Platelet stocks could be maintained if buffy coat production was increased to 49% (normally 29%). If a more extreme scenario is modelled e.g. the clinical attack rate is increased to 50%, red cell stock would fall to 4 k (without further demand reduction) and platelet stock could only be maintained if buffy coat production is increased to 85%. Conclusion This model is useful in illustrating the impact of flu planning assumptions on the ability of the NBS to maintain supply of red cells and platelets and could model other scenarios e.g. severe weather conditions or terrorist activity. As more information becomes available, the NBS and other Blood Services can use the model to illustrate the impact of revised assumptions and take appropriate action to mitigate problems. The model can be used to assess potential policy decisions e.g. donor deferral periods and it could be used in real time as a potential pandemic emerges to help inform decision‐making by predicting future stock levels. The model is being further developed to assist NBS and NHSBT in predicting impact on staffing resource levels. While the model is dynamic and easily manipulated the eventual output is determined by the accuracy of the assumptions. The ultimate accuracy of the model and the assumptions will only be fully understood if and when a Flu Pandemic develops.