What you need to know about COVID-19 vaccines
Vaccines work by mimicking an infectious agent – viruses, bacteria or other microorganisms that can cause a disease. This ‘teaches’ our immune system to rapidly and effectively respond against it. Traditionally, vaccines have done this by introducing a weakened form of an infectious agent that allows our immune system to build a memory of it. This way, our immune system can quickly recognize and fight it before it makes us ill. That’s how some of the COVID-19 vaccines have been designed. Other COVID-19 vaccines have been developed using new approaches, which are called messenger RNA, or mRNA, vaccines. Instead of introducing antigens (a substance that causes your immune system to produce antibodies), mRNA vaccines give our body the genetic code it needs to allow our immune system to produce the antigen itself. mRNA vaccine technology has been studied for several decades. They contain no live virus and do not interfere with human DNA. For more information on how vaccines work, please visit WHO .