Vaccines of SARS-CoV-2
As of April 8, 2020, 115 candidate vaccines for COVID-19 were being
tested globally, of which 78 vaccines have been confirmed to be
effective. Among them, 73 vaccines are in the exploratory or preclinical
stage. The most advanced candidates, including mRNA-1273 from Moderna,
Ad5-nCoV from CanSino Biologicals, INO-4800 from Inovio), have recently
entered the clinical development stage. These advanced vaccines can be
used in conjunction with newly developed COVID-19 vaccines (Thanh Le et
al., 2020).
Vaccines work by exposing the body to antigens that do not cause
disease, but trigger an immune response that can block or kill the virus
if a person is infected. At least four types of vaccines are used
against coronaviruses including, virus vaccines, nucleic-acid
vaccines,viral vector vaccines, and protein-based vaccines(Callaway,
2020). To data, many vaccines are in different stages of clinical trials
to evaluate their effectiveness and safety (Figure 2, table 2).
Multiple strategies are applied to produce vaccines against COVID-19.
The commonest is exposed spike (S) glycoprotein or S protein which
serves as the main trigger of neutralizing antibody, such as full-length
S protein or S1 receptor binding domain (RBD) and expressing in
virus-like particles (VLP), DNA or viral vector (Graham, Donaldson, &
Baric, 2013). Our team uncovered a role of a recombinant vaccine for
COVID-19 (A vaccine targeting the RBD of the S protein of SARS-CoV-2
induces protective immunity) last month (J. Yang et al., 2020).
In fact, effective vaccines and treatments against this new virus will
be facilitated by the achievements in developing SARS-CoV vaccines,
MERS-CoV vaccines/therapies, and recent advances in COVID-19 (Dhama et
al., 2020).