There are many types of vaccines being developed for COVID-19. The common aim driving vaccine development is to cause an immune response that is specific to the COVID-19 coronavirus without making us sick. Most COVID-19 vaccines use the coronavirus ‘spike’ protein to cause this immune response. Our immune system recognises this spike protein as foreign and produces important, long lasting immune cells and antibodies. If a vaccinated person becomes exposed to the coronavirus at a later time the immune system will be able to make a faster and better response to protect against disease.
Messenger RNA (mRNA)
mRNA vaccines use a genetic code called RNA – to spark the production of the coronavirus’ specific spike protein. Once the mRNA enters the body’s cells, the cells use the instructions contained in the RNA to make the spike protein. Immune cells then recognise the spike protein as foreign and begins building an immune response against it. The RNA from the vaccine does not change or interact with our DNA in any way.
Data has shown that the vaccine starts working soon after the first dose and has an efficacy rate of 95% seven days after the second dose. This means that about 95% of people who get the vaccine are protected from becoming seriously ill with the virus. This vaccine is for people age 16 and older. It requires two injections given 21 days apart.
Data has shown that the vaccine has an efficacy rate of 94.1%. This vaccine is for people age 18 and older. This vaccine requires two injections given 28 days apart.
Protein based vaccines use a non-infectious component of the coronavirus, usually the spike protein. This protein is found on the surface of the virus and is manufactured in a laboratory. When the vaccine enters the body, immune cells recognise the spike protein as foreign. Immune cells then recognise the spike protein as foreign and begins building an immune response against it.
This type of vaccine triggers a strong immune response to a key part of the virus. It cannot cause an infection because it does not contain a live pathogen, such as a virus. Researchers are investigating whether they can make a recombinant protein subunit vaccine that targets a protein, called the spike protein, that the new coronavirus uses to latch onto and infect cells. Novavax is one company taking this approach, using nanoparticle technology.
Vector vaccines use a harmless, weakened animal virus that contains the genetic code for a protein unique to the coronavirus, usually the spike protein. This weakened animal virus is known as a viral vector. Once the viral vector enters the body, it instructs our cells to make the coronavirus spike protein. Using these instructions, our cells make copies of the protein. Our immune cells then recognise the spike protein as foreign and begins building an immune response against.
This type acts as a platform for carrying genes that the body can express to provide immunity. The AstraZeneca vaccine, which has approval in some countries, is a replication-incompetent vector vaccine. It uses a harmless, weakened adenovirus that causes the common cold in chimpanzees to provoke an immune response. The scientists then changed the virus to make it suitable for use in humans. In other vaccines, this type of virus has safely produced a strong immune response.