Conference Coverage

ART traces in donor samples show risk to blood supply


 

REPORTING FROM AABB 2019

SAN ANTONIO, TEX. – Some HIV-positive individuals on antiretroviral therapy continue to attempt blood donation, for reasons that may include ignorance of the risks of transmission, test-seeking behavior, or other unknown motivations to donate despite knowing their viral status, caution investigators who monitor the nation’s blood supply.

Dr. Brian Custer

Additionally, evidence of pre-exposure prophylaxis (PrEP) with antiretroviral agents (ARV) in HIV-negative donors raises concerns about possible risk of transmission from HIV-breakthrough infections, reported Brian S. Custer, PhD, of Vitalant Research Institute.

Dr. Custer and colleagues in the U.S. Transfusion Transmissible Infections Monitoring System (TTIMS) evaluated plasma samples from four large blood collection organizations and found metabolites of drugs typically used in ARV regimens, at concentrations indicating that they had been taken within a week of blood donation.

“What are the motivations of these individuals who are ARV-positive and HIV-positive? Are they using the blood center as a place to monitor their infection status? We just do not know the answer to that, but it does bring back this issue of whether there a form of test seeking going on here,” he said at the annual meeting of AABB, the group formerly known as the American Association of Blood Banks.

The findings suggest that current donor health questionnaires and pre-donation screening are not adequate for ascertaining disclosure of HIV status or behaviors that could put the safety of the blood supply in doubt.

Does ‘U’ really equal ‘U’?

The public health message that “undetectable” equals “untransmittable” may help to prevent new infections, but may not translate into transfusion safety, Dr. Custer said.

Current HIV treatment guidelines recommend that infected individuals start on ARV immediately upon receiving a diagnosis. ARV drugs both suppress viremia and alter biomarkers of HIV progression, and may delay the time to antibody seroconversion, which could affect the ability to detect HIV through blood donation screening.

To see whether there is renewed cause for concern about safety of the blood supply, the TTIMS investigators tested for ARV metabolites in donated blood samples as a surrogate for HIV infection.

They looked at 299 HIV-positive plasma samples and 300 samples negative for all testable infections using liquid chromatography–mass spectometry for metabolites of 13 ARVs.

No ARV metabolites could be detected in the HIV-negative samples, but in 299 samples from 463 HIV-positive donors they found that 46 (15.4%) tested positive for ARVs. Of these 46 specimens, 43 were from first-time donors, and 34 were from males. Three samples were from repeat donors.

In all, 41 of the 46 ARV-positive donors would have been considered as potential “elite controllers” – HIV-infected individuals with no detectable viral loads in the absence of therapy – based on HIV-positive serology but negative nucleic acid test (NAT) results.

Samples from five first-time donors tested positive for HIV by both serology and NAT, and also contained ARV metabolites, suggesting that the donors had started ARVs recently, had suboptimal therapy, or were poorly adherent to their regimens.

PrEP use among HIV-negative donors

The investigators also looked at PrEP use in 1494 samples from first-time male donors that tested negative for all markers routinely screened: HIV 1/2, hepatitis B virus, hepatitis C virus, HTLV-I/II, West Nile virus, ZIKV, Treponema pallidum and Trypanosoma cruzi.

The donors came from Boston, Los Angeles, Miami, New York, San Francisco, and Washington, all cities with elevated HIV prevalence and active PrEP rollout campaigns.

They tested for analytes to emtricitabine and tenofovir, the two ARV components of the PrEP drug Truvada, and found that nine samples (0.6%) tested positive for PrEP. Of these, three donors had taken PrEP approximately 1 day before donation, two took it 2 days before, and four took it about 4 days before donation.

“There is quite a bit of concern about what this might mean for blood safety.” Dr. Custer said. “There’s a possibility of a breakthrough infection if someone is not PrEP adherent, and would we be able to detect them? Could this be an additional indicator for the risk of transfusion-transmissible infections? Could we identify subgroups of PrEP use in the donor population, and would we see any evidence?”

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