Human herpesvirus-6 (HHV-6) may cause serious diseases in immunocompromised individuals. SARS-CoV-2/HHV-6 co-infection has been emphasized in previous works, mostly case reports, small series or epidemiological studies, but few is known about its real clinical outcomes. Here we present a real-world pilot study aiming to understand the frequency and the clinical impact of HHV-6 co-infection in moderate to critically ill patients hospitalized due to COVID-19. SARS-CoV-2 and HHV-6 were evaluated in nasopharyngeal samples at the hospital admission of suspected COVID-19 patients. From 173 consecutive cases, 60 were SARS-CoV-2 positive and 13/60 (21.7%) were HHV-6 positive, after identified as the HHV-6B species by a Sanger sequencing. The SARS-CoV-2+/HHV-6+ group was younger but no significant for cardiovascular diseases, diabetes, obesity and cancer, but significant among therapeutic immunosuppressed patients (as systemic lupus erythematous and kidney transplant patients). In the medical records, only sparse data on cutaneous or neurological manifestations were found. Biochemical and hematological data showed only a trend towards hyperferritinemic status and lymphopenia. In conclusion, despite of the impressive high frequency of HHV-6 co-infection in SARS-CoV-2 positive cases, it did not impact general mortality. We suggest larger future prospective studies to better elucidate the influence of HHV-6 reactivation in cases of COVID-19, designed to specific assessment of clinical outcomes and viral reactivation mechanisms. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.

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