SEATTLE — A U.S. volunteer became the first person to receive an experimental COVID-19 vaccine as part of the first phase of humans trial on March 16, the Associated Press reports.

According to Kaiser Permanente, which is funded by the National Institutes of Health to conduct the project, the vaccine eschews dead or inert viruses and instead utilizes messenger RNA, or mRNA.

A previous study in Molecular Theory suggests engineered mRNA could cause ribosomes in human cells to manufacture artificially designed proteins.

According to Kaiser Permanente, their vaccine would make cells produce a protein that is found in the outer coating of SARS-CoV-2, which triggers an immune response.

If a person who received the vaccine is later infected with COVID-19, their prior immune response may help their body mount a stronger reaction to the real virus infection.