When your body is attacked by a virus, your immune system uses white blood cells to search out, identify and produce specialized antibodies to attack the identified germs. After any infection, the body keeps a few white blood cells known as memory cells to remember how to protect your body from the disease. When the same germ is detected later, the body can quickly produce the antibodies to attack them. However, it can take your body several days to mount a proper defense and in that time the infection has had time to spread.
Vaccines were created so that your body already has the instructions to combat the illness before it has encountered it. Vaccines have historically worked by imitating an infection in your body causing your body to create the antibodies needed to combat the illness. The imitation infection is caused by the injection of an altered version of the virus. The virus in the vaccine has either been extremely weakened so it will not cause serious disease or made entirely inactive by killing the germ reducing its ability to replicate and spread throughout the body. After the imitation infection has gone away the body remembers how to combat that disease in the future. Although effective, these vaccines require a lot of development and can sometimes take over a decade to create.
A new type of vaccine seems likely to receive approval for the first time in the US, these are called RNA vaccines. These use Messenger RNA (mRNA), a type of molecules that provide coded instructions for your body’s cells to follow when building proteins. In this case the mRNA is instructing your cells to create a protein found in the virus, triggering your body’s immune response. The protein is the actual part of the Coronavirus which the antibodies recognize when combating the disease. Instead of injecting the weakened virus into a patient to expose your immune system to the proteins scientists have found a way to have your own cells recreate that same protein. When the RNA enters your body’s healthy cells it will begin the production of the proteins and your body will use its immune system to create antibodies just as it would with a conventional vaccine. This new approach to vaccine development is much faster, one company developing an RNA Covid-19 vaccine had doses ready for testing in two months.