Microbiol Spectr . Prolonged SARS-CoV-2 Positivity in Immunocompetent Patients: Virus Isolation, Genomic Integrity, and Transmission Risk

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Microbiol Spectr


. 2021 Nov 17;e0085521.
doi: 10.1128/Spectrum.00855-21. Online ahead of print.
Prolonged SARS-CoV-2 Positivity in Immunocompetent Patients: Virus Isolation, Genomic Integrity, and Transmission Risk


Isabela de Carvalho Leitão ¹ , Pedro Telles Calil ² , Rafael Mello Galliez ³ , Filipe Romero Rebello Moreira ⁴ , Diana Mariani ⁴ , Anna Carla Pinto Castiñeiras ⁵ , Gustavo Peixoto Duarte da Silva ² , Richard Araújo Maia ⁴ , Isadora Alonso Corrêa ² , Fábio Luís Lima Monteiro ² , Marcos Romário Matos de Souza ² , Cássia Cristina Alves Gonçalves ⁴ , Luiza Mendonça Higa ⁴ , Liane de Jesus Ribeiro ⁴ , Vinicius Wakoff Pereira Fonseca ⁴ , Victoria Cortes Bastos ³ , Carolina Moreira Voloch ⁴ , Débora Souza Faffe ¹ , Orlando da Costa Ferreira Jr ⁴ , Amilcar Tanuri ⁴ , Terezinha Marta Pereira Pinto Castiñeiras ^{# 3} , Luciana Jesus da Costa ^{# 2} , on the behalf of the UFRJ-Covid19 Workgroup



Affiliations

• PMID: 34787498
• DOI: 10.1128/Spectrum.00855-21

Abstract

Current guidelines for patient isolation in COVID-19 cases recommend a symptom-based approach, averting the use of control real-time reverse transcription PCR (rRT-PCR) testing. However, we hypothesized that patients with persistently positive results by RT-PCR for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be potentially infectious for a prolonged time, even if immunocompetent and asymptomatic, which would demand a longer social isolation period than presently recommended. To test this hypothesis, 72 samples from 51 mildly symptomatic immunocompetent patients with long-lasting positive rRT-PCR results for SARS-CoV-2 were tested for their infectiousness in cell culture. The serological response of samples from those patients and virus genomic integrity were also analyzed. Infectious viruses were successfully isolated from 34.38% (22/64) of nasopharynx samples obtained 14 days or longer after symptom onset. Indeed, we observed successful virus isolation up to 128 days. Complete SARS-COV-2 genome integrity was demonstrated, suggesting the presence of replication-competent viruses. No correlation was found between the isolation of infectious viruses and rRT-PCR cycle threshold values or the humoral immune response. These findings call attention to the need to review current isolation guidelines, particularly in scenarios involving high-risk individuals. IMPORTANCE In this study, we evaluated mildly symptomatic immunocompetent patients with long-lasting positive rRT-PCR results for SARS-CoV-2. Infectious viruses were successfully isolated in cell cultures from nasopharynx samples obtained 14 days or longer after symptom onset. Indeed, we observed successful virus isolation for up to 128 days. Moreover, SARS-CoV-2 genome integrity was demonstrated by sequencing, suggesting the presence of replication-competent viruses. These data point out the risk of continuous SARS-CoV-2 transmission from patients with prolonged detection of SARS-CoV-2 in the upper respiratory tract, which has important implications for current precaution guidelines, particularly in settings where vulnerable individuals may be exposed (e.g., nursing homes and hospitals).

Keywords: COVID-19; COVID-19 nucleic acid testing; SARS-CoV-2; immunocompetent; persistence; virus shedding.