A vaccine is essentially a mimicked infection, bacteria, virus. In order to create a vaccine you need to know enough about the infection to be able to mimic it.
Vaccines harmlessly show viruses or bacteria (or even small parts of them) to the immune system. The body’s defences recognise them as an invader and learn how to fight them.
Then if the body is ever exposed for real, it already knows what to do.
The main method of vaccination for decades has been to use the original virus.
The measles, mumps and rubella (MMR) vaccine is made by using weakened viruses that cannot cause a full-blown infection. The seasonal flu jab takes the main strains of flu doing the rounds and completely disables them.
The work on a new coronavirus vaccine is using newer, and less tested, approaches called “plug and play” vaccines. Because we know the genetic code of the new coronavirus, Sars-CoV-2, we have the complete blueprint for building it.
Researchers in Oxford have put small sections of its genetic code into a harmless virus that infects chimpanzees. They hope they have developed a safe virus that looks enough like the coronavirus to produce an immune response.
Other groups are using pieces of raw genetic code (either DNA or RNA depending on the approach) which, once injected into the body, should start producing bits of viral proteins which the immune system again can learn to fight.