Zhang Xian, Chen Liting, Wang Gaoxiang, Chen Liwen, Huang Lifang, Cao Yang, Chen Xing, Deng Chaohua, Chen Xuhui, Ke Dandan, Qin Yuanjun, Chen Bo, Sun Xufang
Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
Department of Hematology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
Infect Drug Resist. 2021 Dec 15;14:5395-5401. doi: 10.2147/IDR.S335635. eCollection 2021.
This study detects SARS-CoV-2 in the ocular surface through one-step reverse-transcription droplet digital PCR (one-step RT-ddPCR) and evaluates the possibility of the ocular surface as a possible transmission route.
A single-center prospective observational study was designed to investigate the viral loads in ocular surface. Specimens including the conjunctival swabs, nasopharyngeal swabs and blood were synchronously collected at a single time point for all COVID-19 patients. SARS-CoV-2 loads in nasopharyngeal swabs were tested by real-time polymerase chain reaction (PCR); the blood samples and conjunctival swabs were tested by real-time PCR and one-step RT-ddPCR.
Sixty-eight COVID-19 patients confirmed by nasopharyngeal real-time PCR were recruited. In the single time point test, 40 cases showed positive SARS-CoV-2 detection in either the blood, tears, or nasopharynx, of which four cases were triple-positive, 10 were dual-positive, and 26 were single-positive. The positive rate of nasopharyngeal swab real-time PCR test was 22.1% (15/68). The positive rate of blood and conjunctival swabs by one-step RT-ddPCR was 38.2% (26/68) and 25% (17/68), respectively, whereas real-time PCR was all negative. Positive conjunctival swabs were significantly correlated with positive nasopharyngeal swabs ( = 0.028). The sampling lags from illness onset to sampling day in 3 out of 4 triple-positive patients and in 9 out of 10 dual-positive patients were respectively less than 9 days and less than 20 days.
Our results indicate that the positive rate of SARS-CoV-2 on the ocular surface is much higher than expected. Transmission possibility through the ocular surface may be greatly underestimated.
本研究通过一步法逆转录液滴数字PCR（一步法RT-ddPCR）检测眼表中的严重急性呼吸综合征冠状病毒2（SARS-CoV-2），并评估眼表作为可能传播途径的可能性。
设计一项单中心前瞻性观察性研究，以调查眼表中的病毒载量。在单个时间点为所有冠状病毒病2019（COVID-19）患者同步采集包括结膜拭子、鼻咽拭子和血液在内的标本。通过实时聚合酶链反应（PCR）检测鼻咽拭子中的SARS-CoV-2载量；通过实时PCR和一步法RT-ddPCR检测血液样本和结膜拭子。
招募了68例经鼻咽实时PCR确诊的COVID-19患者。在单次时间点检测中，40例患者的血液、泪液或鼻咽中SARS-CoV-2检测呈阳性，其中4例为三阳性，10例为双阳性，26例为单阳性。鼻咽拭子实时PCR检测的阳性率为22.1%（15/68）。一步法RT-ddPCR检测血液和结膜拭子的阳性率分别为38.2%（26/68）和25%（17/68），而实时PCR检测均为阴性。结膜拭子阳性与鼻咽拭子阳性显著相关（ = 0.028）。4例三阳性患者中有3例、10例双阳性患者中有9例从发病到采样日的采样滞后时间分别小于9天和小于20天。
我们的结果表明，眼表上SARS-CoV-2的阳性率远高于预期。通过眼表传播的可能性可能被大大低估。
