Testing for HCV Infection: An Update of Guidance for Clinicians and Laboratorians

Information sourced from CDC:

Morbidity and Mortality Weekly Report (MMWR)

Weekly May 10, 2013 / 62(18);362-365 [Link to free full-text MMWR article PDF]

Testing for HCV Infection: An Update of Guidance for Clinicians and Laboratorians

[EXCERPTS]

In 2012, CDC amended testing recommendations to include one-time HCV testing for all persons born during 1945 €“1965 regardless of other risk factors.

CDC is issuing this update in guidance because of 1) changes in the availability of certain commercial HCV antibody tests, 2) evidence that many persons who are identified as reactive by an HCV antibody test might not subsequently be evaluated to determine if they have current HCV infection, and 3) significant advances in the development of antiviral agents with improved efficacy against HCV.

Changes in HCV Testing Technologies

Since the 2003 guidance was published, there have been two developments with important implications for HCV testing:

  • Availability of a rapid test for HCV antibody. The OraQuick HCV Rapid Antibody Test (OraSure Technologies) is a rapid assay for the presumptive detection of HCV antibody in fingerstick capillary blood and venipuncture whole blood. Its sensitivity and specificity are similar to those of FDA €“approved, laboratory-conducted HCV antibody assays. In 2011, a Clinical Laboratory Improvements Amendments waiver was granted to the test by FDA. The waiver provides wider testing access to persons at risk for HCV infection, permitting use of the assay in nontraditional settings such as physician offices, hospital emergency departments, health department clinics, and other freestanding counseling and testing sites.
  • Discontinuation of RIBA HCV. The Chiron RIBA HCV 3.0 Strip Immunoblot Assay (Novartis Vaccines and Diagnostics) that was recommended for supplemental testing of blood samples after initial HCV antibody testing is no longer available. As a result, the only other FDA-approved supplemental tests for HCV infection are those that detect HCV viremia.

Identifying Current HCV Infections

Because antiviral treatment is intended for persons with current HCV infection, these persons need to be distinguished from persons whose infection has resolved. HCV RNA in blood, by nucleic acid testing (NAT), is a marker for HCV viremia and is detected only in persons who are currently infected. Persons with reactive results after HCV antibody testing should be evaluated for the presence of HCV RNA in their blood.

Benefits of Testing for Current HCV Infection

Accurate testing to identify current infection is important to 1) help clinicians and other providers correctly identify persons infected with HCV, so that preventive services, care and treatment can be offered; 2) notify tested persons of their infection status, enabling them to make informed decisions about medical care and options for HCV treatment, take measures to limit HCV-associated disease progression (e.g., avoidance or reduction of alcohol intake, and vaccination against hepatitis A and B), and minimize risk for transmitting HCV to others; and 3) inform persons who are not currently infected of their status and the fact that they are not infectious.

Recommended Testing Sequence

* For persons who might have been exposed to HCV within the past 6 months, testing for HCV RNA or follow-up testing for HCV antibody is recommended. For persons who are immunocompromised, testing for HCV RNA can be considered.

€  To differentiate past, resolved HCV infection from biologic false positivity for HCV antibody, testing with another HCV antibody assay can be considered. Repeat HCV RNA testing if the person tested is suspected to have had HCV exposure within the past 6 months or has clinical evidence of HCV disease, or if there is concern regarding the handling or storage of the test specimen.

TABLE. Interpretation of results of tests for hepatitis C virus (HCV) infection and further actions

Test outcome Interpretation Further action
HCV antibody nonreactive No HCV antibody detected Sample can be reported as nonreactive for HCV antibody. No further action required.If recent HCV exposure in person tested is suspected, test for HCV RNA.*
HCV antibody reactive Presumptive HCV infection A repeatedly reactive result is consistent with current HCV infection, or past HCV infection that has resolved, or biologic false positivity for HCV antibody. Test for HCV RNA to identify current infection.
HCV antibody reactive, HCV RNA detected Current HCV infection Provide person tested with appropriate counseling and link person tested to medical care and treatment. € 
HCV antibody reactive, HCV RNA not detected No current HCV infection No further action required in most cases.If distinction between true positivity and biologic false positivity for HCV antibody is desired, and if sample is repeatedly reactive in the initial test, test with another HCV antibody assay.

In certain situations § follow up with HCV RNA testing and appropriate counseling.

* If HCV RNA testing is not feasible and person tested is not immunocompromised, do follow-up testing for HCV antibody to demonstrate seroconversion. If the person tested is immunocompromised, consider testing for HCV RNA. €  It is recommended before initiating antiviral therapy to retest for HCV RNA in a subsequent blood sample to confirm HCV RNA positivity.

§ If the person tested is suspected of having HCV exposure within the past 6 months, or has clinical evidence of HCV disease, or if there is concern regarding the handling or storage of the test specimen.

[Link to free MMWR article PDF for full text, tables, and references]

Centers for Disease Control and Prevention
https://www.cdc.gov/

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