Many providers use severe acute respiratory coronavirus virus 2 (SARS-CoV-2) cycle thresholds (Ct values) as approximate measures of viral burden in association with other clinical data to inform decisions about treatment and isolation. We characterized temporal changes in Ct values for non–SARS-CoV-2 respiratory viruses as a first step to determine whether cycle thresholds could play a similar role in the management of non–SARS-CoV-2 respiratory viruses.

Retrospective cohort study.

Brigham and Women’s Hospital, Boston.

We retrospectively identified all adult patients with positive nasopharyngeal PCRs for influenza, respiratory syncytial virus (RSV), parainfluenza, human metapneumovirus (HMPV), rhinovirus, or adenovirus between January 2022 and March 2023. We plotted Ct distributions relative to days since symptom onset, and we assessed whether distributions varied by immunosuppression and other comorbidities.

We analyzed 1,863 positive samples: 506 influenza, 502 rhinovirus, 430 RSV, 219 HMPV, 180 parainfluenza, 26 adenovirus. Ct values were generally 25–30 on the day of symptom onset, lower over the ensuing 1–3 days, and progressively higher thereafter with Ct values ≥30 after 1 week for most viruses. Ct values were generally higher and more stable over time for rhinovirus. There was no association between immunocompromised status and median intervals from symptom onset until Ct values were ≥30.

Ct values relative to symptom onset for influenza, RSV, and other non–SARS-CoV-2 respiratory viruses generally mirror patterns seen with SARS-CoV-2. Further data on associations between Ct values and viral viability, transmissibility, host characteristics, and response to treatment for non-SARS-CoV-2 respiratory viruses are needed to determine how clinicians and infection preventionists might integrate Ct values into treatment and isolation decisions.

许多提供者使用严重急性呼吸道冠状病毒 2 (SARS-CoV-2) 周期阈值（Ct 值）作为病毒负荷的近似测量值，并与其他临床数据相结合，为有关治疗和隔离的决策提供信息。我们表征了非 SARS-CoV-2 呼吸道病毒 Ct 值的时间变化，作为确定循环阈值是否可以在非 SARS-CoV-2 呼吸道病毒管理中发挥类似作用的第一步。

回顾性队列研究。

波士顿布莱根妇女医院。

我们回顾性地识别了 2022 年 1 月至 2023 年 3 月期间鼻咽部 PCR 检测呈流感、呼吸道合胞病毒 (RSV)、副流感、人类偏肺病毒 (HMPV)、鼻病毒或腺病毒阳性的所有成年患者。我们绘制了相对于症状出现后天数的 Ct 分布，我们评估了分布是否因免疫抑制和其他合并症而变化。

我们分析了 1,863 个阳性样本：506 个流感病毒、502 个鼻病毒、430 个 RSV、219 个 HMPV、180 个副流感病毒、26 个腺病毒。症状出现当天的 Ct 值一般为 25-30，随后 1-3 天较低，此后逐渐升高，大多数病毒 1 周后 Ct 值≥30。随着时间的推移，鼻病毒的 Ct 值通常更高且更稳定。免疫功能低下状态与从症状出现到 Ct 值≥30 的中位间隔之间没有关联。

与流感、RSV 和其他非 SARS-CoV-2 呼吸道病毒症状发作相关的 Ct 值通常反映了 SARS-CoV-2 的模式。需要有关 Ct 值与病毒活力、传播性、宿主特征以及对非 SARS-CoV-2 呼吸道病毒治疗反应之间关系的进一步数据，以确定临床医生和感染预防人员如何将 Ct 值纳入治疗和隔离决策。