As part of INTERVAL, we’ve asked participants to provide research blood samples on joining the study and, again, after 2 years. These samples will be used to see if there are differences in the iron status of donors giving blood more or less often over a 2-year period and, so, provide evidence on optimum donation intervals for donor health over the longer-term. It’s also highly desirable to support these findings with information on how blood donors’ haemoglobin levels and iron stores are restored in the shorter-term i.e. across successive donations. This is information will allow the prediction of haemoglobin and iron levels at a donation session from measurements taken at a previous session; this will help to develop future donation management strategies to optimise donors’ health and experiences of giving blood.

So, we are recruiting approximately 4,000 existing INTERVAL participants to give a small, additional blood sample at each of their future donation appointments during their remaining time on the INTERVAL study. This new ‘Phase’ of the study is called INTERVAL Phase III.

In order to meet the aims of INTERVAL Phase III we will be sending invites to those INTERVAL participants who:

  1. Do not have an existing donation deferral at the time of joining the Phase III
  2. Have enough time remaining on the study to give a minimum of 2 consecutive research samples at their study-allocated donation frequency

INTERVAL Phase II participants receiving appointment reminders through NHSBT’s routine systems will **NOT** be invited to Phase III. This is because Phase III will require a more “active approach” to reminders which would impact on this group’s valuable contribution to an important question being addressed in INTERVAL Phase II.

The Phase III invitation will be sent by email and will provide full details about taking

provide full details about taking part as well as an online consent form. However, if you would like to learn more about Phase III now, please click here.