HIV

HIV Testing Algorithm with separate detection of Ag and Ab

Incubation period Acute Phase Asymptomatic Phase Symptomatic Phase
Description 2 – 4 weeks "flu-like" symptoms
  • progressive depletion of CD4+ T-cells
  • can last >10 years
  • AIDS develops
  • Common symptoms: chills, fever, sweats, swollen lymph glands, weakness, and weight loss
CD4+ T-cells normal low declining low to depleted
p24 antigen rising high - high
anti-HIV - rising high high
HIV RNA rising high fluctuating high
Contagious - highly moderately highly

Adapted from:

  1. Fiebig EW, et al. Dynamics of HIV viremia and antibody seroconversion in plasma donors: implications for diagnosis and staging of primary HIV infection. AIDS. 2003;17:1871-9.
  2. Cohen MS, et al. Acute HIV-1 Infection. N Engl J Med. 2011;364:1943-54.
  3. De Jong MD, et al. Clinical, virological and immunological features of primary HIV-1 infection. Genitourin Med. 1991;67:367-73.
Product Description Tests Product page
Elecsys® HIV combi PT a) Electrochemiluminescence immunoassay (ECLIA) for the qualitative detection of HIV-1 p24 antigen and antibodies to HIV-1 and HIV-2 in human serum and plasma 100
200
Elecsys® HIV Duo b) Electrochemiluminescence immunoassay (ECLIA) for the qualitative detection of HIV-1 p24 antigen and antibodies to HIV-1 and HIV-2 in human serum and plasma 300
cobas® HIV-1 c) Nucleic acid amplification test for the quantitation of human immunodeficiency virus type 1 (HIV-1) in EDTA plasma or from a cobas® Plasma Separation Card (PSC) dried plasma spot of HIV-1-infected individuals 96
cobas® HIV-1 d) 192
cobas® HIV-1 e) Nucleic acid amplification test for the quantitation of human immunodeficiency virus type 1 (HIV-1) in EDTA plasma of HIV-1-infected individuals 120
cobas® HIV-1/HIV-2 Qualitative Test d) Nucleic acid amplification test for the qualitative detection and differentiation of HIV-1 and HIV-2 in human serum, plasma, and dried blood spots (DBS). 120

a) for use on the cobas® e 411 analyzer and the cobas® e 601 / 602 modules
b) for use on the cobas® e 402 and cobas® e 801 analytical units
c) for use on the cobas® 6800/8800 Systems
d) for use on the cobas® 5800/6800/8800 Systems
e) for use on the cobas® 4800 System

Adapted from:

  1. U.S. Department of Health and Human Services, Centers for Disease Control and Prevention (CDC). Laboratory Testing for the Diagnosis of HIV Infection: Updated Recommendations. [Internet; updated 2014 Jun 27; cited 2023 Nov]. Available from: http://dx.doi.org/10.15620/cdc.23447.
  2. Alexander TS. Human Immunodeficiency Virus Diagnostic Testing: 30 Years of Evolution. Clin Vaccine Immunol. 2016;23:249-253.
  3. European Centre for Disease Prevention and Control (ECDC). HIV testing in Europe. Evaluation of the impact of the ECDC guidance on HIV testing: increasing uptake and effectiveness in the European Union. [Internet; updated 2016; cited 2023 Nov]. Available from: https://op.europa.eu/en/publication-detail/-/publication/b6a6d67a-d896-11e6-ad7c-01aa75ed71a1/language-en.
  4. Rijksinstituut voor Volksgezondheid and Milieu (National Institute for Health and Environment of the Netherlands). Draaiboek voor Centra Seksuele Gezondheid in de Publieke Gezondheidszorg (Script for Sexual Health Centers in Public Healthcare). [Internet; updated 2024 Feb 26; cited 2024 Mar 4]. Available from: https://lci.rivm.nl/draaiboeken/consult-seksuele-gezondheid.
  5. Haute Autorité de Santé (HAS). Dépistage de l’infection par le VIH en France - Stratégies et dispositif de dépistage (Screening for HIV infection in France - Screening strategies and facilities. [Internet; updated 2009 Oct; cited 2024 Mar 4]. Available from: https://sante.gouv.fr/IMG/pdf/argumentaire_depistage_vih_HAS_2009-2.pdf.
  • Step 1
  • Step 2
  • Step 3
  • Step 4
Step 1

Perform HIV-1/2 p24-antigen and antibody combination test
​​​​​​​(HIV 4th generation immunoassay)

HIV antibody
HIV antigen
  • Step 1
  • Step 2
  • Step 3
  • Step 4
Step 2

Perform Western Blot (HIV-1/2, O)
​​​​​​​or 3rd generation test

Western Blot /
3rd gen test

  • Step 1
  • Step 2
  • Step 3
  • Step 4
Step 2

Perform confirmatory HIV antigen or
​​​​​​​HIV qualitative RNA test

HIV Ag / HIV RNA test
  • Step 1
  • Step 2
  • Step 3
  • Step 4
Step 3

Perform 2nd confirmation -
HIV 4th generation assay

HIV confirmatory test
  • Step 1
  • Step 2
  • Step 3
  • Step 4
Step 3

Perform 2nd confirmation -
HIV 4th generation assay

HIV confirmatory test
  • Step 1
  • Step 2
  • Step 3
  • Step 4

Summary

No indication of an HIV infection

In case the clinical background indicates an acute HIV infection, repeat the HIV-1/2 Ag/Ab combination test after 1-2 weeks. If this result is again negative there is no laboratory evidence of HIV infection.

In case the clinical background does not indicate an acute HIV infection, but there might be a risk of infection, repeat the HIV-1/2 Ag/Ab combination test after 3-4 weeks and 3 months (because of the window phase).

  • Step 1
  • Step 2
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  • Step 4

Summary

Initial reactive screening result not confirmed

A non-reactive or indeterminate HIV-1/HIV-2 antibody test result indicates a false-positive result on the initial immunoassay.

Follow-up testing for HIV-1 RNA should be performed if clinically indicated. In case the clinical background indicates an acute HIV infection, repeat the HIV-1/2 Ag/Ab combination test after 2-3 weeks.

  • Step 1
  • Step 2
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  • Step 4

Summary

Initial reactive screening result not confirmed

A negative HIV-1 RNA result indicates a false-positive result on the initial immunoassay.

Follow-up testing for HIV-2 should be performed if clinically indicated. In case the clinical background indicates an acute HIV infection, repeat the HIV-1/2 Ag/Ab combination test after 2-3 weeks.

  • Step 1
  • Step 2
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  • Step 4

Summary

Inconclusive result

Retest in 1-3 weeks.

  • Step 1
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  • Step 4

Summary

Confirmed HIV infection
  • Step 1
  • Step 2
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  • Step 4

Summary

Inconclusive result

​​​​​​​Retest in 1-3 weeks.

  • Step 1
  • Step 2
  • Step 3
  • Step 4

Summary

Confirmed HIV infection
Back
Next Restart simulation
Step
Result
Interpretation
1
HIV antibody test = ...
HIV antigen test = ...
waiting for input
1
HIV antibody test = negative
HIV antigen test = negative

No indication of an HIV infection

1
HIV antibody test = negative
HIV antigen test = positive
Possible HIV infection

In case the clinical background indicates an acute HIV infection, Perform confirmatory HIV antigen or qualitative HIV-1 RNA test.

In case the clinical background does not indicate an acute HIV infection, repeat the HIV HIV-1/2 Ag/Ab combination test in 2-3 weeks or perform directly an HIV-1 RNA test.
1
HIV antibody test = positive
HIV antigen test = negative

Possible HIV infection

Perform Western Blot (HIV-1/2, O) or 3rd generation test.

1
HIV antibody test = positive
HIV antigen test = positive

Possible HIV infection

Perform Western Blot (HIV-1/2, O) or 3rd generation test.

2
Western Blot / 3rd gen test = ...
waiting for input
2
Western Blot / 3rd gen test = non-reactive or indeterminate

Initial reactive screening result not confirmed​​​​​​​

2

Western Blot / 3rd gen test = positive

Chronic HIV infection

Perform 2nd confirmation – HIV 4th generation assay to exclude errors

2
HIV Ag / HIV RNA test = ...
waiting for input
2
HIV Ag / HIV RNA test = negative

Initial reactive screening result not confirmed

A negative HIV-1 RNA result indicates a false-positive result on the initial immunoassay. Follow-up testing for HIV-2 should be performed if clinically indicated. In case the clinical background indicates an acute HIV infection, repeat the HIV-1/2 Ag/Ab combination test after 2-3 weeks.

2
HIV Ag / HIV RNA test = positive

Acute HIV infection

Perform 2nd confirmation – HIV 4th generation assay to exclude errors

3
HIV 4th generation test = ...
waiting for input
3
HIV 4th generation test = negative

Inconclusive result​​​​​​​

3

HIV 4th generation test = positive

Confirmed HIV infection.
3
HIV 4th generation test = ...
waiting for input
3
HIV 4th generation test = negative

Inconclusive result

​​​​​​​Retest in 1-3 weeks

3

HIV 4th generation test = positive

Confirmed HIV infection

End of test sequence