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).