1.1 Patients
In order to identify asymptomatic individuals, the Disease Control and
Prevention (CDC) of Loudi conducted total of
1,844 close contacts (mean age
38.2± 19.9 years old), including 1,003 males (mean age 38.7 ± 19.9 years
old) and 841 females (mean age 37.7 ± 20.0 years) with 76 confirmed
patients with COVID-19 from January to May 2020. Nasopharyngeal swabs
were collected for SARS-CoV-2 nucleic acid detection from all close
contacts. Participants then submitted to a 14-day medical quarantine
observation period. Asymptomatic cases who received two consecutively
negative nucleic acid tests after the expiration of medical quarantine
were observed at home for an additional 14 days. Asymptomatic cases were
defined by a positive result from SARS-CoV-2 nucleic acid detection of
respiratory tract specimens or serum specific IgM antibodies without
corresponding clinical symptoms of COVID-19 in close contacts, based
on the diagnostic criteria for
COVID-19 and the requirements of the treatment plan (trial version 6 and
trial version 7) issued by the National Health Commission of the
People’s Republic of China and National Administration of Traditional
Chinese Medicine [4, 5].
26 cases without clinical symptoms within 28 days of observation were
recruited from close contacts following a positive SARS-CoV-2 nucleic
acid detection. Close contacts whose nucleic acid test results were
negative continued to be isolated for additional 14 days observation.
50 cases of healthy individuals
from the First Hospital of Hunan University of Chinese Medicine served
as the control group. Age and gender distribution did not differ between
the study group and the control group (p>0.05). The details
information of cases was presented in the results section. This study
was approved by Ethics Committee of the First Hospital of Hunan
University of Chinese Medicine.