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RNA loads of severe acute respiratory syndrome coronavirus 2 in patients with breakthrough coronavirus disease 2019 caused by the Delta and Omicron variants.
de Michelena, Paula; Torres, Ignacio; Ferrando, Enric-Cuevas; Olea, Beatriz; González-Candelas, Fernando; Sánchez, Gloria; Navarro, David.
  • de Michelena P; Microbiology Service, Clinic University Hospital, Instituto de Investigación Sanitaria Hospital Clínico Valencia Health Research Institute, Valencia, Spain.
  • Torres I; Microbiology Service, Clinic University Hospital, Instituto de Investigación Sanitaria Hospital Clínico Valencia Health Research Institute, Valencia, Spain.
  • Ferrando EC; Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, Instituto de Agroquímica y Tecnología de Alimentos-Centyro Superior de Investigaciones Científicas, Valencia, Spain.
  • Olea B; Microbiology Service, Clinic University Hospital, Instituto de Investigación Sanitaria Hospital Clínico Valencia Health Research Institute, Valencia, Spain.
  • González-Candelas F; Joint Research Unit Infection and Public Health Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana-University of Valencia, Institute for Integrative Systems Biology (I2SysBio, Universitat de València-Centyro Superior de Investigaciones Científicas) and Cen
  • Sánchez G; Department of Preservation and Food Safety Technologies, Institute of Agrochemistry and Food Technology, Instituto de Agroquímica y Tecnología de Alimentos-Centyro Superior de Investigaciones Científicas, Valencia, Spain.
  • Navarro D; Microbiology Service, Clinic University Hospital, Instituto de Investigación Sanitaria Hospital Clínico Valencia Health Research Institute, Valencia, Spain; Department of Microbiology, School of Medicine, University of Valencia, Valencia, Spain. Electronic address: david.navarro@uv.es.
Clin Microbiol Infect ; 2022 Sep 15.
Article in English | MEDLINE | ID: covidwho-2229361
ABSTRACT

OBJECTIVES:

To compare the RNA loads of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal specimens collected from patients with breakthrough coronavirus disease 2019 (COVID-19) caused by the Delta variant with those in specimens collected from patients with breakthrough COVID-19 caused by the Omicron variant.

METHODS:

A retrospective, observational study was conducted, including 240 consecutive adult out-patients, of whom 121 (74 females; median age, 40 years) had COVID-19 due to the Omicron variant and 119 (65 females; median age, 48 years) had COVID-19 caused by the Delta variant. The viral RNA load was quantitated using the TaqPath COVID-19 Combo Kit (Thermo Fisher Scientific, Waltham, MS, USA). The viability platinum chloride reverse transcription-PCR assay was used to discriminate between potentially infectious viral particles and free (encapsidated) viral RNA.

RESULTS:

Overall, the viral RNA loads were significantly higher (p 0.003) for the Omicron variant (median, 8.1 log10 copies/mL; range, 4.0-10.9 log10 copies/mL) than for the Delta variant (median, 7.5 log10 copies/mL; range, 3.0-11.6 log10 copies/mL). A trend towards higher viral loads was noticed for Omicron compared with that for Delta across the following time frames since vaccination 16-90 days (median, 6.83 vs. 5.88 log10 copies/mL, respectively; range, 3.91-10.68 vs. 3.67-9.66 log10 copies/mL, respectively; p 0.10), 91-180 days (median, 8.09 vs. 7.46 log10 copies/mL, respectively; range, 4.30-10.92 vs. 3.03-11.56 log10 copies/mL, respectively; p 0.003) and 181-330 days (median, 8.56 vs. 8.10 log10 copies/mL, respectively; range, 6.51-10.29 vs. 3.03-10.61 log10 copies/mL, respectively; p 0.11). The platinum chloride treated or untreated reverse transcription-PCR cycle threshold ratio for the nucleocapsid gene as the target was slightly higher for Omicron than for Delta (median, 0.62 vs. 0.57, respectively; range, 0.57-0.98 vs. 0.61-0.87, respectively), although statistical significance was not reached (p 0.10).

CONCLUSION:

The time elapsed since vaccination has a major impact on the RNA loads of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal specimens, particularly for the Omicron variant. The Omicron variant may be better adapted for replication in the upper respiratory tract than the Delta variant, in which this is unlikely given its more efficient generation of viral particles.
Keywords

Full text: Available Collection: International databases Database: MEDLINE Type of study: Observational study / Prognostic study Topics: Vaccines / Variants Language: English Journal subject: Communicable Diseases / Microbiology Year: 2022 Document Type: Article Affiliation country: J.cmi.2022.09.003

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Full text: Available Collection: International databases Database: MEDLINE Type of study: Observational study / Prognostic study Topics: Vaccines / Variants Language: English Journal subject: Communicable Diseases / Microbiology Year: 2022 Document Type: Article Affiliation country: J.cmi.2022.09.003