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Multiple unconfirmed-reactive screening tests for viral antibodies among blood donors
J Buffington1, C N Shapiro, R C Holman
1Division of Viral and Rickettsial Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
Insights
Unconfirmed blood test reactivity for viruses like HCV increased seasonally and was linked to specific test kits, not solely influenza vaccination. This suggests test-specific factors influence screening results.
Area of Science:
- Infectious Disease Epidemiology
- Clinical Laboratory Science
- Public Health Surveillance
Background:
- Reports of unconfirmed reactivity in blood donations for HIV, HTLV-I, and HCV antibodies were investigated.
- A significant proportion of donors with unconfirmed reactivity reported recent influenza vaccination.
Purpose of the Study:
- To assess the prevalence and temporal trends of unconfirmed blood donation reactivity.
- To identify associations between unconfirmed reactivity and specific screening test manufacturers.
Main Methods:
- A nationwide survey of 110 blood centers screened 14 million donations from May 1990 to December 1991.
- Case-donations were defined as repeatedly reactive but not confirmed positive results on at least two of three screening tests.
Main Results:
- 582 case-donations were identified, with rates increasing significantly in 1991.
- A higher rate of case-donations was observed with one specific anti-HCV screening test (8.0 vs. 1.2/100,000 donations).
Conclusions:
- Unconfirmed reactivity showed seasonal patterns but also test-specific influences, as seen before influenza vaccine availability.
- Factors related to specific anti-HCV test kits contributed to the observed unconfirmed reactivity rates.
Background:
In December 1991, the United States Food and Drug Administration received reports of blood donations with unconfirmed reactivity on screening tests for antibodies to human immunodeficiency virus, human T-lymphotropic virus type I, and hepatitis C virus (HCV). Of 91 donors with these test results, 57 (63%) reported a recent influenza vaccination.
Study Design And Methods:
To determine the extent of unconfirmed reactivity, the time at which it began, and its association or nonassociation with specific manufacturers' tests, a nationwide survey of blood centers was conducted. A case-donation was defined as a blood donation that was repeatedly reactive, but not confirmed positive, on at least two of the three tests from May 1990 through December 1991.
Results:
Among 14 million donations screened by 110 centers, 582 case-donations were identified. An increase in case-donations was evident in the fall of 1990 (2.8/100,000 donations). In 1991, rates increased from 0.9 per 100,000 donations in the first quarter to 1.3, 3.2, and 19.7 in subsequent quarters. A significantly higher rate of case-donations was observed among donations tested with one of the two available anti-HCV screening tests (8.0 vs. 1.2/100,000 donations; risk ratio = 6.8; 95% CI = 5.4-8.5).
Conclusion:
Although unconfirmed reactivity on multiple screening tests appeared to be seasonal, its documentation prior to the availability of influenza vaccine in 1991 and higher rates among donations tested with one manufacturer's anti-HCV test indicated that test-specific factors were also involved.
