Chien Ai, Domeracki Sandra, Guntur Sandeep, Taylor Kristopher, Lu Chuanyi M, Lampiris Harry, Blanc Paul D
Occupational and Employee Health Section and Infectious Disease Section, Medical Service and Laboratory Medicine Service, San Francisco Veterans Affairs Health Care System, 4150 Clement St., San Francisco, CA, 94121, USA.
Division of Occupational and Environmental Medicine, Department of Medicine, University of California San Francisco, San Francisco, USA.
J Occup Med Toxicol. 2021 Aug 4;16(1):29. doi: 10.1186/s12995-021-00321-3.
Household SARS-COV-2 contact constitutes a high-risk exposure for health care workers (HCWs). Cycle threshold (Ct) of reverse transcriptase-polymerase chain reaction testing provides an estimate of COVID-19 viral load, which can inform clinical and workplace management. We assessed whether Ct values differed between HCWs with COVID-19 with and without household exposure.
We analyzed HCW COVID-19 cases whose Ct data could be compared. We defined low Ct at a cut-point approximating a viral load of 4.6 × 10 copies per ml. Logistic regression tested the association of household exposure and symptoms at diagnosis with a low Ct value.
Of 77 HCWs with COVID-19, 20 were household exposures cases and 34 were symptomatic at testing (7 were both household-exposed and symptomatic at testing). Among household exposures, 9 of 20 (45%) manifested lower Ct values compared to 14 of 57 (25%) for all others. In a bivariate model, household exposure was not statistically associated with lower Ct (Odds Ratio [OR] 1.20; 95% Confidence Interval [CI] 0.97-1.51). In multivariable modelling both household exposure (OR] 1.3; 95% CI 1.03-1.6) and symptoms at diagnosis (OR 1.4; 95% CI 1.15-1.7) were associated with a low Ct value.
Household exposure in HCWs with newly diagnosed COVID-19 was associated with lower Ct values, consistent with a higher viral load, supporting the hypothesis that contracting COVID-19 in that manner leads to a greater viral inoculum.
家庭中接触严重急性呼吸综合征冠状病毒2（SARS-CoV-2）对医护人员构成高风险暴露。逆转录聚合酶链反应检测的循环阈值（Ct）可估算2019冠状病毒病（COVID-19）病毒载量，这可为临床和工作场所管理提供参考。我们评估了有家庭暴露史和无家庭暴露史的COVID-19医护人员的Ct值是否存在差异。
我们分析了Ct数据可比较的医护人员COVID-19病例。我们将低Ct定义为接近每毫升4.6×10拷贝病毒载量的切点。逻辑回归检验家庭暴露和诊断时的症状与低Ct值之间的关联。
在77例COVID-19医护人员中，20例为家庭暴露病例，34例在检测时有症状（7例在检测时既为家庭暴露又有症状）。在家庭暴露病例中，20例中有9例（45%）Ct值较低，而其他所有病例中57例中有14例（25%）Ct值较低。在二元模型中，家庭暴露与较低Ct无统计学关联（优势比[OR]1.20；95%置信区间[CI]0.97 - 1.51）。在多变量模型中，家庭暴露（OR 1.3；95% CI 1.03 - 1.6）和诊断时的症状（OR 1.4；95% CI 1.15 - 1.7）均与低Ct值相关。
新诊断为COVID-19的医护人员的家庭暴露与较低Ct值相关，这与较高的病毒载量一致，支持以这种方式感染COVID-19会导致更大病毒接种量的假说。
