The Pfizer and Moderna vaccines use a technology called mRNA, which stands for Messenger Ribonucleic Acid. This technology has been around for decades.
mRNA is like the instruction manual for your cells, telling them how to make proteins we need to survive. The vaccine uses mRNA to tell our body how to make a harmless piece of the spike protein that is on the COVID-19 virus.
Your body then starts attacking the spike protein and learns how to defend against it.
mRNA does not affect your DNA. The body gets rid of mRNA as soon as it is finished using the instructions to make the spike protein.
The delivery mechanism for the mRNA is, small particles called lipids, which help deliver the mRNA safely to the cells.
MRNA vaccines come in two doses spaced three to four weeks apart. The second dose acts as a booster to keep training your immune system so it doesn't forget.
Johnson and Johnson uses a slightly different technology. It uses a modified version of the virus that causes the common cold. This virus is called an adenovirus. It has been changed so that you won't get a cold or any other illness. This technology has been around for over 50 years.
The modified adenovirus delivers a section of DNA from the COVID-19 virus to your cells. The cells start producing the harmless COVID-19 spike protein.
Your immune system begins attacking the spike protein and learns how to defend against it so that when it comes across the real virus, your body knows how to fight back.
Johnson and Johnson only requires one shot.