Additional sections

Three appendices have been produced with this guide that include more technical details about HIV testing.

Print copies of this booklet do not include these sections.

These additional 14 pages are only available in the online and PDF versions.

Appendix 1: Different types of HIV test

This section explains in detail the difference between the main types of tests used to test for HIV and when they are used.

These are:

  • Antigen only (p24 tests). These are rarely used.
  • Antibody only tests (Ab). These are rarely used because of more recent availability of joint Ag/Ab tests.
  • Combined antibody-antigen tests. These are the most commonly recommended tests in the UK. These test for both antibodies to HIV and p24.
  • Viral load tests (RNA PCR test)

Viral load tests are not approved to diagnose HIV but are sometimes used in some circumstances.

Link to Appendix 1.

Appendix 2: Theoretical risk, population risk & individual risk

This section discuss the differences between individual risk and population risk. Sometimes what is a very small individual risk may still not be acceptable for many people.

It also includes a brief section about how difficult it is to judge risks and how we approach the idea of risk in daily life.

Link to Appendix 2.

Appendix 3: How HIV tests work

This section describes how HIV tests work in more detail.

Sometimes i-Base is asked technical details and so these might be useful for some people.

This section talks about antigens and antibodies and explains how each of these tests work.

It also explains the differences between Elisa and western blot tests.

It also includes more detailed information and the timing of different stages of early infection and seroconversion.

Link to Appendix 3.

Last updated: 1 June 2021.