---
title: "Detection of Nirsevimab-Resistant RSV-B Variant (F:K68Q) in Adult ICU Patient"
id: "pubmed-42734717"
canonical_url: "https://medichelpline.com/clinical-feed/pubmed-42734717"
content_type: "clinical_feed_article"
specialty: "Critical Care"
source_name: "PubMed / NCBI"
source_url: "https://pubmed.ncbi.nlm.nih.gov/42734717/"
doi: "10.1007/s40121-026-01442-0"
published_at: "2026-09-14T00:00:00.000Z"
evidence_level: "Journal Article"
license: "CC-BY-NC-4.0 / Informational Use"
---
# Detection of Nirsevimab-Resistant RSV-B Variant (F:K68Q) in Adult ICU Patient
## Provenance & Clinical Metadata
- **Canonical URL:** https://medichelpline.com/clinical-feed/pubmed-42734717
- **Specialty:** [Critical Care](https://medichelpline.com/clinical-feed/critical-care.md)
- **Primary Source:** PubMed / NCBI
- **Source URL:** [Original Journal Publication](https://pubmed.ncbi.nlm.nih.gov/42734717/)
- **DOI:** [10.1007/s40121-026-01442-0](https://doi.org/10.1007%2Fs40121-026-01442-0)
- **Published At:** 2026-09-14T00:00:00.000Z
- **Evidence Rating:** Journal Article
## Executive GIST (TL;DR)
- A case from the prospective ARF-RSV cohort (NCT06197152) describes a 64-year-old man with aggressive mantle cell lymphoma on active treatment who required ICU admission for severe sepsis during febrile aplasia. - Two nasopharyngeal samples taken 7 days apart tested positive for **RSV-B** by genetic analysis. - Both samples were assigned to lineage B.D.E.1 and harbored a dominant **F:K68Q** substitution in the viral fusion protein, detected at allele frequencies of 99% and 97% with sequencing coverage >170×. - The **F:K68Q** substitution has been previously associated with high-level resistance to the monoclonal antibody **nirsevimab**. - The patient’s hemodynamic failure resolved within a few days and clinical evolution was rapidly favorable despite severe infection and immunosuppression. - The report notes that **F:K68Q** appears rare among circulating RSV strains; the abstract does not provide broader prevalence data or detailed clinical management beyond sampling and sequencing results. - This finding raises concerns about potential antiviral or prophylactic monoclonal-antibody escape in vulnerable adult populations, particularly immunocompromised patients considered for future use of prefusion F–targeting antibodies. - Additional epidemiologic and phenotypic data, including functional resistance testing and population prevalence, were not reported in the abstract.
## Clinical Analysis & Structured Key Points
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Online ahead of print. # Detection of a Nirsevimab-Resistant RSV-B Variant (F:K68Q) in an Adult with Severe Infection [Nicolas de Prost](https://pubmed.ncbi.nlm.nih.gov/?term=de+Prost+N&cauthor_id=42734717)[ 1 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-1 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France. nicolas.de-prost@aphp.fr.")[ 2 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-2 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France. nicolas.de-prost@aphp.fr.")[ 3 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-3 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France. nicolas.de-prost@aphp.fr."), [Marie Le Goff](https://pubmed.ncbi.nlm.nih.gov/?term=Le+Goff+M&cauthor_id=42734717)[ 4 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-4 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France.")[ 5 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-5 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France."), [Pierre Cappy](https://pubmed.ncbi.nlm.nih.gov/?term=Cappy+P&cauthor_id=42734717)[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Pierre Bay](https://pubmed.ncbi.nlm.nih.gov/?term=Bay+P&cauthor_id=42734717)[ 4 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-4 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France.")[ 5 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-5 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France."), [Mélissa N'debi](https://pubmed.ncbi.nlm.nih.gov/?term=N%27debi+M&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Alexandre Soulier](https://pubmed.ncbi.nlm.nih.gov/?term=Soulier+A&cauthor_id=42734717)[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Jean-Michel Pawlotsky](https://pubmed.ncbi.nlm.nih.gov/?term=Pawlotsky+JM&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Christophe Rodriguez](https://pubmed.ncbi.nlm.nih.gov/?term=Rodriguez+C&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Slim Fourati](https://pubmed.ncbi.nlm.nih.gov/?term=Fourati+S&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#full-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France.") Affiliations Expand ### Affiliations * 1 Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris (AP-HP), 1, rue Gustave Eiffel, 94010, Créteil, France. nicolas.de-prost@aphp.fr. * 2 Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil (UPEC), Créteil, France. nicolas.de-prost@aphp.fr. * 3 IMRB INSERM U955, Team >, Université Paris-Est-Créteil (UPEC), Créteil, France. nicolas.de-prost@aphp.fr. * 4 Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris (AP-HP), 1, rue Gustave Eiffel, 94010, Créteil, France. * 5 Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil (UPEC), Créteil, France. * 6 IMRB INSERM U955, Team >, Université Paris-Est-Créteil (UPEC), Créteil, France. * 7 Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France. * PMID: **42734717** * DOI: [ 10.1007/s40121-026-01442-0 ](https://doi.org/10.1007/s40121-026-01442-0) Item in Clipboard # Detection of a Nirsevimab-Resistant RSV-B Variant (F:K68Q) in an Adult with Severe Infection Nicolas de Prost et al. Infect Dis Ther. 2026. Show details Display options Display options Format Abstract PubMed PMID Infect Dis Ther Actions * [ Search in PubMed ](https://pubmed.ncbi.nlm.nih.gov/?term=%22Infect+Dis+Ther%22%5Bjour%5D&sort=date&sort_order=desc) * [ Search in NLM Catalog ](https://www.ncbi.nlm.nih.gov/nlmcatalog?term=%22Infect+Dis+Ther%22%5BTitle+Abbreviation%5D) * [ Add to Search ](https://pubmed.ncbi.nlm.nih.gov/42734717/) . 2026 Sep 14. doi: 10.1007/s40121-026-01442-0. Online ahead of print. ### Authors [Nicolas de Prost](https://pubmed.ncbi.nlm.nih.gov/?term=de+Prost+N&cauthor_id=42734717)[ 1 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-1 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France. nicolas.de-prost@aphp.fr.")[ 2 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-2 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France. nicolas.de-prost@aphp.fr.")[ 3 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-3 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France. nicolas.de-prost@aphp.fr."), [Marie Le Goff](https://pubmed.ncbi.nlm.nih.gov/?term=Le+Goff+M&cauthor_id=42734717)[ 4 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-4 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France.")[ 5 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-5 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France."), [Pierre Cappy](https://pubmed.ncbi.nlm.nih.gov/?term=Cappy+P&cauthor_id=42734717)[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Pierre Bay](https://pubmed.ncbi.nlm.nih.gov/?term=Bay+P&cauthor_id=42734717)[ 4 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-4 "Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris \(AP-HP\), 1, rue Gustave Eiffel, 94010, Créteil, France.")[ 5 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-5 "Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France."), [Mélissa N'debi](https://pubmed.ncbi.nlm.nih.gov/?term=N%27debi+M&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Alexandre Soulier](https://pubmed.ncbi.nlm.nih.gov/?term=Soulier+A&cauthor_id=42734717)[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Jean-Michel Pawlotsky](https://pubmed.ncbi.nlm.nih.gov/?term=Pawlotsky+JM&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Christophe Rodriguez](https://pubmed.ncbi.nlm.nih.gov/?term=Rodriguez+C&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France."), [Slim Fourati](https://pubmed.ncbi.nlm.nih.gov/?term=Fourati+S&cauthor_id=42734717)[ 6 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-6 "IMRB INSERM U955, Team >, Université Paris-Est-Créteil \(UPEC\), Créteil, France.")[ 7 ](https://pubmed.ncbi.nlm.nih.gov/42734717/#short-view-affiliation-7 "Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France.") ### Affiliations * 1 Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris (AP-HP), 1, rue Gustave Eiffel, 94010, Créteil, France. nicolas.de-prost@aphp.fr. * 2 Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil (UPEC), Créteil, France. nicolas.de-prost@aphp.fr. * 3 IMRB INSERM U955, Team >, Université Paris-Est-Créteil (UPEC), Créteil, France. nicolas.de-prost@aphp.fr. * 4 Service de Médecine Intensive Réanimation, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris (AP-HP), 1, rue Gustave Eiffel, 94010, Créteil, France. * 5 Groupe de Recherche Clinique CARMAS, Université Paris-Est-Créteil (UPEC), Créteil, France. * 6 IMRB INSERM U955, Team >, Université Paris-Est-Créteil (UPEC), Créteil, France. * 7 Department of Virology, Hôpitaux Universitaires Henri Mondor, Assistance Publique - Hôpitaux de Paris, Créteil, France. * PMID: **42734717** * DOI: [ 10.1007/s40121-026-01442-0 ](https://doi.org/10.1007/s40121-026-01442-0) Item in Clipboard Cite Display options Display options Format Abstract PubMed PMID ## Abstract **Introduction:** Respiratory syncytial virus (RSV) is recognized as a major cause of severe disease in adults, particularly those having cardiorespiratory comorbidities or immunosuppression. The recent deployment of monoclonal antibodies targeting the prefusion F protein could be used in the future to prevent RSV-associated hospitalization and critical illness in immunocompromised adult patients. **Methods:** This report is part of the ongoing ARF-RSV study ([NCT06197152](http://clinicaltrials.gov/show/NCT06197152 "See in ClinicalTrials.gov")), a prospective, multicenter observational cohort. **Results:** We report on the case of a 64-year-old man with a previous medical history of aggressive mantle cell lymphoma under active treatment who was admitted to the intensive care unit for severe sepsis in the setting of febrile aplasia. Clinical evolution was rapidly favorable, with resolution of hemodynamic failure within a few days. Two nasopharyngeal samples collected 7 days apart were positive for RSV-B. Genetic analysis identified a strain belonging to lineage B.D.E.1, with both samples harboring a dominant F:K68Q substitution in the fusion protein. In the first sample, the mean depth of coverage was over 180× and the F:K68Q substitution was detected at an allele frequency of 99%. In the second sample, collected 7 days later, the mean depth of coverage was 170×, with the same substitution detected with an allele frequency of 97%, consistent with persistence as a dominant variant over time. This substitution has been previously associated with high-level resistance to nirsevimab. More generally, F:K68Q appears to be rare among circulating RSV
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