These photos capture the world's first human trial of a potential coronavirus vaccine

Four healthy people were the first to get a trial COVID-19 vaccine on Monday.

The vaccine was administered to patients at the Kaiser Permanente Washington Health Research Institute in Seattle.

Forty-five volunteers will be apart of the clinical trial. The volunteers who were selected were screened by Kaiser to not be sick nor have underlying health conditions. However, they were not screened for whether or not someone might have had a mild case of COVID-19.

It will take at least a year to 18 months to determine if a vaccine for the novel coronavirus is safe and effective, National Institutes of Health experts have said.

Some of the participants may get a higher dosage of the vaccine, to see what dosage is most effective.

Volunteers will be given two doses. The second dose will be administered a month after the first.

This potential vaccine was developed by the National Institute of Health and the private biotech company Moderna.

The vaccine was created in 42 days.

The test vaccine works by producing harmless "spike" proteins, which will prompt the body to create antibodies. If a person were to be exposed to the real coronavirus, their body would be prepared to react quickly, as spike proteins are what allow the novel coronavirus to attach themselves to human cells.

If approved, it would be first to use just the virus' "messenger RNA" sequence and not the actual virus itself. The vaccine won't infect participants with the coronavirus that causes COVID-19 since the vaccine doesn't use the virus.

While participants don't risk getting the virus, the safety of the vaccine is still unknown. Scientists don't know what the immune response to the test will be yet.

While this is the first potential vaccine to make it into a clinical human trial, other vaccines are also underway. Before any vaccine becomes available to the general public, researchers have to be sure it is safe and effective.