National strategies and algorithms are used for HIV testing to accurately identify infections. There are three main testing strategies: 1. Strategy 1 is for blood/organ donation safety and uses a highly sensitive test. If reactive, the unit is discarded. Donors are referred for counseling and confirmation testing. 2. Strategy 2A is for anonymous surveillance and requires two reactive ELISA/rapid tests to be reported positive. 3. Strategy 3 is for asymptomatic diagnosis and uses two ELISA/rapid tests followed by a tiebreaker. An indeterminate result requires repeat testing in 2-4 weeks. The strategies involve serial or parallel testing with different tests to confirm results based on each situation and ensure accurate and ethical

1. National Strategies and Algorithms For
HIV Testing
Dr. Arkadeb Kar
Post-graduate Trainee
Calcutta National Medical College And Hospital

2. • A testing strategy refers to selecting the best type of test, or more than
one type of test, for identifying and confirming HIV infection in a
particular testing situation like:
Blood /Organ donation safety
Surveillance
Diagnosis

3. • Involve a logical sequence of performing two or more tests, one after
the other (serial) or simultaneously (parallel) to arrive at a conclusion
on the HIV status of a person being tested.
• A testing algorithm refers to the combination and sequence of specific
tests that are used to fulfil the testing strategy.
• India's strategy is based on serial testing and includes repeat testing of
initially reactive sample.

4. Objectives
1. Transfusion and transplant safety
2. Diagnosis of HIV infection in symptomatic and asymptomatic
individuals
3. Prevention of parent to child transmission
4. For Post-Exposure Prophylaxis (PEP)
5. Epidemiological surveillance using unlinked anonymous HIV
testing
6. Research

5. Commonly used tests
• Enzyme Linked Immunosorbent Assay (ELISA)
• Rapid tests
 Immunoconcentration/ Dot Blot assay (vertical flow)
 Agglutination assay
 Immunochromatographic assay (lateral flow)
 Dipstick and comb assay based on Enzyme Immune Assay (EIA)
• Confirmatory tests with high specificity, like WBs and line immunoassays, are used in
problem cases, e.g., in cases of indeterminate/discordant result of ELISA /Rapid tests.

6. Testing policies to be considered:
• Testing should be part of the overall comprehensive prevention programme.
• Testing should be technically sound and appropriate.
• Testing procedures must be field appropriate.
• Testing procedures must be cost effective.
• Laboratory procedures must be monitored to ensure quality.

7. Strategy 1 (for blood transfusion/transplant safety)
 The test used in strategy 1 must have high sensitivity.
 The unit of blood that tests reactive (positive) is discarded.
 If the donor is to be notified of his result, based on his prior consent, it becomes a matter of diagnosis (in
which case strategies II & III must be used after proper counselling) and the donor should be referred to an
ICTC for the confirmation of the result

8. Strategy 2 A (used in sentinel surveillance)
• This type of HIV testing is anonymous and unlinked.
• It is reported positive only if the second ELISA/rapid test also gives a reactive report like
the first test.

9. Strategy 2 B (used for diagnosis in symptomatic patients)
 where the physician indicates that the patient is suffering
from clinical AIDS like symptoms, the HIV status of the
patient can be confirmed as positive on the basis of two
reactive test results.
 In case a specimen is reactive with the first test kit and
non reactive with the second test kit, the specimen is
subjected to a third tiebreaker test.
 If the third test is reactive, the specimen is reported as
indeterminate and follow up testing is undertaken after 2
to 4 weeks.
 In case the third tiebreaker test is non-reactive, the
specimen is reported negative.
 Counselling, informed consent, and confidentiality are a
must in all these cases

10. Strategy 3 (used for diagnosis in asymptomatic patients)
 If the specimen gives a reactive result with
two E/R and non-reactive result with the
third assay, it is reported as “indeterminate”
and the patient is called again for repeat
testing after 2-4 weeks
 The test utilized for the first screening
should be the one with the highest
sensitivity and those used for the second
and third tests are those with the highest
specificity
 This strategy is used for the diagnosis of
HIV infection in asymptomatic individuals
at ICTCs and PPTCT centres.
 Testing should be repeated on a second
specimen taken after 14-28 days. In case the
serological results continue to be
indeterminate, then the specimen is to be
subjected to a WB/PCR if facilities are
available or refer to the NRL for further
testing.