Fig. 4.

Different types of vaccines used for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). A) mRNA vaccine works by using a piece of mRNA that corresponds to a viral protein. After receiving the mRNA vaccination, human cells will produce a foreign viral protein. As part of the normal immune system, the immune system of the body will be able to recognize the foreign viral protein and will start to produce antibodies against the foreign viral protein. These antibodies will protect humans against SARS-CoV-2 infection. B) In the DNA vaccine, genetic material from the SARS-CoV-2 is placed in an altered form (viral vector). When this viral vector is injected into cells, it will deliver the genetic material of SARS-CoV-2 and will start to produce a foreign viral protein. The normal immune system of the body will recognize the foreign viral protein and will start produce antibodies against the foreign viral protein. These antibodies will protect humans against SARS-CoV-2 infection. C) Protein subunit vaccine. This vaccine includes only slices of a virus, which stimulates the immune response. This vaccine contains harmless S protein and once our body recognizes the S proteins, it will create antibodies and defensive white blood cells. If humans infected with SARS-CoV-2, these antibodies would fight against the SARS-CoV-2.