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BackEntry title:

Transfusion transmitted infections (TTI) surveillance (episodes investigated)

Last updated on Thursday, 16 July 2026 at 10:13am

Summary

Topic
transfusion-safety
Category
API name
safety_testing_investigated

Rationale

The joint NHS Blood and Transplant (NHSBT) and UK Health Security Agency (UKHSA) Epidemiology Unit monitors suspected transfusion transmitted infections (TTIs).

This work covers blood donors and recipients across the four UK blood services:

  • NHS Blood and Transplant
  • Welsh Blood Service
  • Northern Ireland Blood Transfusion Service
  • Scottish National Blood Transfusion Service

The unit works with Serious Hazards of Transfusion (SHOT). The data helps inform and assess policies that protect people who receive blood transfusions. The UKHSA data dashboard only includes confirmed TTIs.

Definition

Confirmed TTIs are shown by the year the transfusion took place. A suspected infection is classed as a confirmed TTI when:

  • the recipient showed evidence of infection after receiving a blood transfusion
  • there was no evidence that they had the infection before the transfusion
  • there was no evidence of another source of infection

At least one of the following must also apply:

  • a blood component received by the recipient came from a donor with evidence of the same infection
  • a blood component received by the recipient was shown to contain the infectious agent

Methodology

An infection may be identified when:

  • a recipient develops an infection, and the transfusion is the suspected source
  • a post transfusion infection is reported to a blood service

An infection may also be found through a lookback investigation. This happens when a repeat donor has markers of infection.

During a lookback investigation archived samples may be tested. Testing may show that an earlier donation was also positive but that the level of infection was too low to be detected during routine screening.

Further work is then carried out to identify recipients who received blood from that donation.

TTIs found through lookback investigations are not currently included in this dashboard.

Caveats

European Union legislation defines a serious adverse reaction as a reaction in a patient that:

  • is life threatening
  • causes disability or incapacity
  • results in hospital admission
  • prolongs a hospital stay
  • causes illness

Blood services must report these reactions to the Medicines and Healthcare products Regulatory Agency. This is a legal requirement. Reports must include all suspected, probable and confirmed TTIs.

Blood services in England, Wales, Northern Ireland and Scotland report suspected TTI investigations to the Epidemiology Unit each year. Each report includes information about:

  • the recipient
  • the infection
  • the transfusion linked to the investigation
  • the investigation outcome, such as confirmed, probable, possible or near miss

The Epidemiology Unit compares its data with SHOT data. All blood service investigations with an outcome are included in the TTI chapter of the SHOT annual report. The data is also published in:

  • the UKHSA Health Protection Report
  • the NHSBT and UKHSA Epidemiology Unit annual review

The dashboard shows data by year of transfusion. Data is available from 1996, when surveillance began. For more information, see the Epidemiology Unit's annual review, as well as the annual SHOT report.

Caveats

Suspected incidents are not reported to SHOT when:

  • they involve hepatitis C, HIV or HTLV in recipients who received a transfusion in the UK before routine testing started
  • they involve HTLV in a recipient identified through the HTLV National Lookback
  • the transfusion took place outside the UK
  • the incident was identified through the hepatitis E virus study

Routine testing started in:

  • September 1991 for hepatitis C antibodies
  • October 1985 for HIV antibodies
  • August 2002 for HTLV antibodies

This is a live reporting database. The data may change and may differ from other published reports.