Introduction
In December 2019, an unexplained viral pneumonia broke out in Wuhan,
Hubei Province, China [1, 2]. The origin of the
novel coronavirus remains unknown. However, gene sequencing analysis
showed the virus was closely related to the coronavirus detected in wild
animals. The novel coronavirus, named the severe acute respiratory
syndrome coronavirus 2 (SARS-CoV-2) by the International Committee on
Taxonomy of Viruses, causing the Corona Virus Disease 2019 (COVID-19),
termed by the World Health Organization (WHO) [3].
COVID-19 has a lower mortality rate, is more contagious, and has caused
a higher death toll than severe acute respiratory syndrome (SARS). These
factors have led to a global pandemic within only a few months. At
present, the epidemic in China has been well controlled due to a series
of effective measures taken by the Chinese government, but it is still
spreading abroad. The main challenge faced by the word in the future, in
terms of the prevention and control of the epidemic, is the quick and
accurate identification of the asymptomatic infection of SARS-CoV-2.
A positive result from a nucleic acid test is important for the
diagnosis of asymptomatic patients with SARS-CoV-2 infection. Real-time
fluorescence PCR (RT-PCR) is the main method to
detect viral nucleic acid.
However, the many limitations (i.e. long detection cycle, expensive
reagents, and high requirements for sampling, technicians and laboratory
conditions) can lead to high false negative rates and the untimely
diagnosis and screening of asymptomatic cases. Therefore, there is an
urgent need to explore a rapid, simple, and feasible method for the
diagnosis and screening of COVID-19.
Serum immunoglobulin M (IgM) antibodies appear in the early stages of
viral infection. This is followed by the production of serum
immunoglobulin G (IgG) antibodies. These antibodies are essential for
long-term immunity and immune memory. Detecting serum IgM and IgG
antibodies may provide a valuable detection method for the diagnosis of
COVID-19, especially when screening for asymptomatic infection. The aim
of this study was to provide evidence for screening infection in
asymptomatic patients with COVID-19 through the dynamic analysis of IgM
and IgG levels.