Flu Shot Sparks False HIV Alarm in Dialysis Patient

Medscape

a day ago

False-positive HIV test results following influenza vaccination are rare. However, unexpected cross-reactivity remains a concern in the evolution of vaccine formulations.
After obtaining her annual flu shot, an 82-year-old woman on haemodialysis (HD) was repeatedly discovered to have positive HIV enzyme-linked immunosorbent assay (ELISA) test results without having risk factors, and previously, the test was negative. Only a more detailed medical history revealed a possible unexpected explanation.
A case report by Rayyan Mkahal,MD, a nephrology fellow at the University of Toronto, Toronto, Ontario, Canada, and his colleagues highlights the potential often-overlooked complications associated with the flu vaccine.
The Patient and Her History
The patient presented for HD with end-stage kidney disease on intermittent HD in one of the dialysis centres. Her medical history was otherwise significant for diabetes mellitus and dyslipidaemia. At the start of HD, the HIV ELISA test result was negative. However, 7 months later, during routine testing, she was unexpectedly found to have a positive HIV ELISA. The patient had never received a blood transfusion and was not sexually active. The patient was clinically stable without evidence of active infection, weight loss, night sweats, fever, chills, or other systemic symptoms. She has no reported recent travel.
Findings and Diagnosis
On admission, her vital signs, including blood pressure, heart and respiratory rates, oxygen saturation on room air, and temperature, were all within normal limits. Complete blood cell count was within the normal range. Otherwise, her immunisation history included a hepatitis B vaccine before initiating dialysis and yearly flu vaccination, the most recent of which was administered approximately 45 days before detection. Her previous COVID booster vaccine was administered 4 months ago. No illnesses, hospitalisations, or major interim events have occurred since dialysis initiation. Other probable causes of false-positive ELISA results, such as autoimmune diseases, malignancy, or recent infections, were considered but were not supported by clinical history or laboratory evaluation. An HIV polymerase chain reaction was performed 14 weeks after the initial positive test and revealed no viral replication. No HIV testing was performed between weeks 3 and 14; therefore, the precise timing of seroconversion remains unknown.
Discussion
'Despite the use of relatively new vaccine formulations, cross-reactivity with ELISA remains a relevant phenomenon. Given that influenza vaccines are given annually, clinicians must remain vigilant to avoid misdiagnosis and treatment. This case highlights the need for increased awareness of this phenomenon and suggests future research to explore the persistence of vaccine-antibody interference in the vulnerable population,' the study authors wrote.