Asymptomatic SARS-CoV-2 infected patients with persistent negative CT findings

Dear editor,

A recent outbreak of coronavirus disease 2019 (COVID-19) in Wuhan, China has become a public health emergency of international concern [1]. As of February 20, 2020, the coronavirus named as severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 has infected more than 75,000 individuals, and caused over 2000 fatal cases.

A previous research reported a familial cluster of COVID-19 pneumonia [2]. In this family, a 10-year-old child had no clinical symptoms, but showed ground glass lung opacification on CT, subsequently, the patient presented positive for the SARS-CoV-2 nucleic acid by real time polymerase chain reaction (RT-PCR). Therefore, these findings indicated the clinical symptoms were not essential components of SARS-CoV-2 infection.

We observed 295 patients with laboratory-identified SARS-CoV-2 infection by RT-PCR between January 23, 2020 and February 18, 2020 in Guangzhou Eighth People’s Hospital. The majority patients had a history of exposure in Wuhan or to infected patients. 49 (17 %) patients presented negative chest CT images at initial presentation; fifteen of 49 patients who had a repeat CT scan that became positive (after 3–6 days) for COVID-19 pneumonia. Thirty-four of 49 patients showed persistent negative CT images (after 3–14 days), and thirty of 34 patients showed few clinical symptoms, 4 patients showed no clinical symptoms. Moreover, two of 4 patients subsequently presented two consecutive negative nucleic acid detection at least 24 h apart and finally recovered (Fig. 1 ).

Fig. 1.

Flowchart of 295 patients screened, 4 (1%) presented negative CT and no clinical symptoms with SARS-CoV-2 infection.

In our observation, we found that four patients with SARS-CoV-2 infection, showed no clinical symptoms or abnormal chest CT images. Lirong Zou et al. [3] reported that the asymptomatic and symptomatic patients showed resemble viral load. The viral RNA can be detected in the respiratory secretions of asymptomatic patients for no less than 5 days. Thus, they suspect that the asymptomatic or few symptomatic patients still have transmission potential.

It is worth noting that, the clinical symptoms and radiological abnormalities are not the essential components of SARS-CoV-2 infection. Therefore, the detection and isolation of infected cases require more careful strategies and screening practices. If some people have a history of exposure to infected areas or contact with patients, regardless of radiological manifestations or clinical symptoms, medical observation and home isolation or SARS-CoV-2 nucleic acid tests are quite important to rule out infection. Medical observation and home isolation for suspected individuals play important roles in timely detecting and containing this emerging communicable disease.

Authors’ contributions

JL, XT and LL designed the study, ZL and XX were major contributors in collecting clinical information of patients and writing the manuscript, QG and LZ revised it critically for important intellectual content. All authors have read and approved the manuscript.

Funding

This work was supported by Key Program of Natural Science Foundation of Guangdong Province of China [Grant Number 2018B0303110011].

Ethics approval

The written informed consent for this retrospective study was waived.

Availability of data and materials

Not applicable.

Code availability

Not applicable.

Declaration of Competing Interest

The authors declare that they have no conflicts of interest.