The COVID-19-associated symptoms are fever, cough, expectoration,
headache, and myalgia
or fatigue. Individuals with asymptomatic and atypical by the University of
Oxford. In a
randomized controlled phase I/II trial, it induced neutralizing antibodies
against SARS-CoV-
2 in all 1,077 participants after a second vaccine dose, while its safety profile
was acceptable
as well'63. The NIAID and Moderna co-manufactured mRNA-1273, a lipid
nanoparticle formulated mRNA vaccine candidate that encodes the stabilized
prefusion SARS-CoV- 2 S protein. Its immunogenicity has been confirmed by
a phase I trial in which robust
neutralizing antibody responses were induced in a dose-dependent manner
and increased after
a second dose'. Regarding inactivated vaccines, a successful phase I/II trial
involving 320
participants has been reported in China. The whole-virus COVID-19 vaccine
had a low rate
of adverse reactions and effectively induced neutralizing antibody
production'. The verified
safety and immunogenicity support advancement of these vaccine
candidates to phase III
clinical trials, which will evaluate their efficacy in protecting healthy
populations from
SARS-CoV-2 infection.
Future perspectives
COVID-19 is the third highly pathogenic human coronavirus disease to date.
Although less
deadly than SARS and MERS, the rapid spreading of this highly contagious
disease has
posed the severest threat to global health in this century. The SARS-CoV-2
outbreak has
lasted for more than half a year now, and it is likely that encircled with an
envelope
containing viral nucleocapsid. The nucleocapsids inCoVs are arranged in
helical symmetry,
which reflects an atypical attribute in positive-sense RNA viruses (30). The
electron
micrographs of SARS-CoV-2 revealed a diverging spherical outline with some
degree of
pleomorphism, virion diameters varying from 60 to 140 nm, and distinct
spikes of 9 to 12
nm, giving the virus the appearance of a solar corona (3). The CoV genome is
arranged
linearly as 5’- leader-UTR- replicase-structural genes (S-E-M-N)-3’ UTR.
poly(A) (32).
Accessory genes, such as 3a/b, 4a/b, and the hemagglutinin-esterase gene
(HE), are also seen
intermingled with the structural genes (30). SARS-CoV-2 has also been found
to be arranged
similarly and encodes several accessory proteins, although it lacks the HE,
which is
characteristic of some beta coronaviruses (31). The positive-sense genome
of CoVs serves as
the mRNA and is translated to polyprotein la/lab (ppla/lab) (33). A replication-
transcription
complex (RTC) is formed in double-membrane vesicles (DMVs) by
nonstructural proteins
(nsps), encoded by the polyprotein gene (34). Subsequently, the RTC
synthesizes a nested set
of sub genomic RNAs (sgRNAs) via discontinuous transcription (35). We also
predict the
possibility of another outbreak, as predicted by Fan et al. (6). Indeed, the
present outbreak
caused by SARS-CoV-2 (COVID- 19) was expected. Similar to previous
outbreaks, the
current outbreak also will be contained shortly. However, the real issue is
how we are
planning to counter the next zoonotic CoV epidemic that is likely to occur
within the next 5
to 10 years or even sooner (Fig. 7). shedding the virus, which may remain
viable for at least 3 days and is considered a great risk for uninfected
patients and health care workers (289). Recently, it was found that the anal
swabs gave more positive results than oral swabs in the later stages of
infection (153). Hence, clinicians have to be cautious while discharging any
COVID-19-infected patient based on negative oral swab test results due to
the possibility of fecal-oral transmission. Even though he viral loads in stool
samples were found to be less than those of respiratory samples, strict
precautionary measures have to be followed while handling stool samples of
COVID-19
