http://www.sciencemag.org/news/2020/12/messenger-rna-gave-us-covid-19-vaccine-will-it-treat-diseases-too

Messenger RNA (blue) directs cells’ ribosomes to make new proteins (red).

The dramatic success of two COVID-19 vaccines in clinical trials last month marked a triumph for a previously unproven medical technology. The vaccines, one of which was authorized for emergency use by the U.S. Food and Drug Administration last week, rely on the genetic instructions known as messenger RNA (mRNA). It prompts cells to make a SARS-CoV-2 protein that trains the immune system to recognize the virus.