P-1647. Duration of SARS-CoV-2 Detection with Rapid Antigen Tests and Nucleic Acid Amplification Tests in a 2024 Nursing Home Resident Cohort

TL;DR

This study compares how long SARS-CoV-2 can be detected in nursing home residents using rapid antigen tests versus more sensitive nucleic acid tests.

Contribution

The study provides updated 2024 data on SARS-CoV-2 detection duration in nursing home residents using rapid antigen and nucleic acid amplification tests.

Findings

Rapid antigen tests detected SARS-CoV-2 for a median of 7 days in nursing home residents.

Nucleic acid amplification tests detected SARS-CoV-2 for a median of 14 days in the same population.

The duration of detection has remained consistent compared to previous seasons.

Abstract

Nursing home (NH) residents are at high risk of contracting and having adverse outcomes from SARS-CoV-2. Based on culture positivity CDC currently recommends 10-day transmission-based precautions; greater understanding of the duration of SARS-CoV-2 detection with rapid antigen tests (RAT) and nucleic acid amplification tests (NAAT), can further guide testing and isolation recommendations to reduce transmission. In a 2023 NH cohort with daily testing, the median duration of SARS-CoV-2 detection among NH residents was six days for RAT and 11 days for NAAT. We update estimates of SARS-CoV-2 detection duration in a 2024 cohort of NH residents to inform prevention efforts.Figure 1:Kaplan-Meier analysis was restricted to residents with ≥4 RAT (n = 88) or NAAT (n = 84). A resident could be in both RAT and NAAT survival curves. The median duration of SARS-CoV-2 detection with RAT was seven days and the median duration of SARS-CoV-2 detection with NAAT was 14 days.

Kaplan-Meier analysis was restricted to residents with ≥4 RAT (n = 88) or NAAT (n = 84). A resident could be in both RAT and NAAT survival curves. The median duration of SARS-CoV-2 detection with RAT was seven days and the median duration of SARS-CoV-2 detection with NAAT was 14 days.

We collected data on NH residents tested for SARS-CoV-2 with RAT and NAAT in 17 NHs across eight states. Residents could enroll upon a positive SARS-CoV-2 RAT or NAAT followed by paired nasal specimen collection every 3-5 days for up to 30 days. We abstracted resident clinical characteristics from available medical records. We used Kaplan-Meier (KM) survival analysis to estimate the time from first positive (day 0) to first negative. We restricted analyses to residents with ≥ 4 RAT or NAAT to capture the duration of SARS-CoV-2 positivity; residents could be in both RAT and NAAT survival curves. We used Greenwood’s formula to calculate 95% confidence intervals (CI).

We enrolled 121 residents with a positive SARS-CoV-2 test, of whom 87 (72%) were vaccinated. Eighty-five participants (70%) had a Charlson Comorbidity Index score ≥5. Sixty-eight participants received antivirals (n=36 [53%] molnupiravir; n=28 [41%] nirmatrelvir/ritonavir; n=4 [6%] remdesivir). The KM analysis included 88 (73%) and 84 (69%) residents with ≥ 4 RAT and NAAT, respectively. The median duration of SARS-CoV-2 detection with RAT was seven days; 61% and 21% had SARS-CoV-2 detection at five and 10 days, respectively (Figure 1). The median duration of SARS-CoV-2 detection with NAAT was 14 days; 94% and 75% had SARS-CoV-2 detection at five and 10 days, respectively.

The median time from first positive to first negative test for NH residents with RAT was 7 days and 14 days for NAAT. The duration of SARS-CoV-2 detection among NH residents has not substantially changed since last season.

Yasin Abul, MD, CDC/ABT: Grant/Research Support|CLARIO: Advisor/Consultant|GSK: Grant/Research Support|Moderna: Grant/Research Support|Seqirus: Grant/Research Support David Canaday, MD, Moderna: Grant/Research Support|Pfizer: Grant/Research Support|Seqirus: Advisor/Consultant|Seqirus: Grant/Research Support|Seqirus: Honoraria Christopher J. Crnich, MD, PhD, Merck: Grant/Research Support Samantha Fuller, MPH, AstraZeneca: Grant/Research Support|CSL Vifor: Grant/Research Support|GlaxoSmithKline: Grant/Research Support Jon P. Furuno, PhD, Merck: Grant/Research Support Stefan Gravenstein, MD, MPH, GSK: Advisor/Consultant|GSK: Grant/Research Support|GSK: Honoraria|Moderna: Grant/Research Support|Novavax: Advisor/Consultant|Novavax: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Pfizer: Honoraria|Sanofi: Advisor/Consultant|Sanofi: Grant/Research Support|Sanofi: Honoraria|Seqirus: Grant/Research Support Jennifer K. Meece, PhD, CSL Seqirus: Grant/Research Support|GSK: Grant/Research Support|ModernaTX: Grant/Research Support Lona Mody, MD, MS, Nanovibronix: Grant/Research Support|NIH, CDC, VA: Grant/Research Support|UpToDate: Honoraria Morgan Katz, MD, MHS, Skinclique: Advisor/Consultant

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