Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam.
Oxford University Clinical Research Unit, Ho Chi Minh City, Vietnam.
Clin Infect Dis. 2020 Dec 17;71(10):2679-2687. doi: 10.1093/cid/ciaa711.
Little is known about the natural history of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.
We conducted a prospective study at a quarantine center for coronavirus disease 2019 in Ho Chi Minh City, Vietnam. We enrolled quarantined people with reverse-transcription polymerase chain reaction (RT-PCR)-confirmed SARS-CoV-2 infection, collecting clinical data, travel and contact history, and saliva at enrollment and daily nasopharyngeal/throat swabs (NTSs) for RT-PCR testing. We compared the natural history and transmission potential of asymptomatic and symptomatic individuals.
Between 10 March and 4 April 2020, 14 000 quarantined people were tested for SARS-CoV-2; 49 were positive. Of these, 30 participated in the study: 13 (43%) never had symptoms and 17 (57%) were symptomatic. Seventeen (57%) participants imported cases. Compared with symptomatic individuals, asymptomatic people were less likely to have detectable SARS-CoV-2 in NTS collected at enrollment (8/13 [62%] vs 17/17 [100%]; P = .02). SARS-CoV-2 RNA was detected in 20 of 27 (74%) available saliva samples (7 of 11 [64%] in the asymptomatic group and 13 of 16 [81%] in the symptomatic group; P = .56). Analysis of RT-PCR positivity probability showed that asymptomatic participants had faster viral clearance than symptomatic participants (P < .001 for difference over the first 19 days). This difference was most pronounced during the first week of follow-up. Two of the asymptomatic individuals appeared to transmit SARS-CoV-2 to 4 contacts.
Asymptomatic SARS-CoV-2 infection is common and can be detected by analysis of saliva or NTSs. The NTS viral loads fall faster in asymptomatic individuals, but these individuals appear able to transmit the virus to others.
无症状严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的自然史知之甚少。
我们在越南胡志明市的 2019 年冠状病毒病检疫中心进行了一项前瞻性研究。我们招募了经逆转录聚合酶链反应（RT-PCR）确诊 SARS-CoV-2 感染的被隔离者，收集临床数据、旅行和接触史以及在入组时和每天采集的唾液进行 RT-PCR 检测。我们比较了无症状和有症状个体的自然史和传播潜力。
在 2020 年 3 月 10 日至 4 月 4 日期间，对 14000 名被隔离者进行了 SARS-CoV-2 检测；49 例呈阳性。其中 30 人参加了这项研究：13 人（43%）从未出现症状，17 人（57%）出现症状。17 名（57%）参与者为输入性病例。与有症状的个体相比，无症状个体在入组时采集的 NTS 中更不可能检测到 SARS-CoV-2（8/13 [62%] vs 17/17 [100%]；P=0.02）。在 27 份可获得的唾液样本中，20 份（74%）检测到 SARS-CoV-2 RNA（无症状组 7/11 [64%]，有症状组 13/16 [81%]；P=0.56）。RT-PCR 阳性率分析显示，无症状参与者的病毒清除速度快于有症状参与者（第 19 天之前的差异 P<0.001）。这种差异在随访的第一周最为明显。2 名无症状个体似乎将 SARS-CoV-2 传播给了 4 名接触者。
无症状 SARS-CoV-2 感染很常见，可通过分析唾液或 NTS 进行检测。无症状个体的 NTS 病毒载量下降更快，但这些个体似乎能够将病毒传播给其他人。
