What is a Vaccine?
A vaccine is a substance that stimulates your immune system to make antibodies -- blood proteins produced in response to a foreign substance -- as it would if you were exposed to the actual disease. After vaccination, you develop immunity to the disease, so you are protected from getting sick if you get infected.
How do the vaccines work?
The vaccines from Pfizer and Moderna use a technique known as mRNA, or messenger RNA. These vaccines "give instructions for our cells to make a harmless piece of what is called the 'spike protein,' " according to the CDC. This protein is found on the surface of the coronavirus that causes COVID-19.
The vaccine from Janssen/Johnson & Johnson is made using a type of virus called adenovirus type 26, or Ad26. The Ad26 delivers a piece of the DNA, or genetic material, used to make the spike protein, so the person can temporarily make this protein and teach the immune system to react against the coronavirus. Ad26 is modified so it can't make the person sick.
How long does the protection last?
Because the vaccines are new, this is not yet known for sure. Based on other viruses that are similar to the coronavirus that causes COVID-19, the COVID-19 vaccines that are shown to be highly effective might protect people for a few years.
