The first human clinical trial of a COVID-19 vaccine was administered Monday. Four volunteers were given their first of two shots of the vaccine. Forty-five volunteers are expected to participate in this trial. The vaccine won’t be available to the general public for at least a year as it’s tested for safety and efficacy. The novel coronavirus, which causes the infectious disease known as COVID-19, has infected more than 182,000 people worldwide and killed more than 7,100.

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 part of the clinical trial. The volunteers who were selected were screened by Kaiser to not be sick nor have underlying health conditions. They were not screened, however, for mild cases of COVID-19.

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

To see which dosage is most effective, some of the participants may get a higher dosage of the vaccine.

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

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

The vaccine was created in 42 days.

The test vaccine works by producing harmless “spike” proteins meant to prompt the body to create antibodies. The idea is that 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 virus itself. The vaccine won’t infect participants with the coronavirus that causes COVID-19.

While participants don’t risk getting the virus, the safety of the vaccine is still unknown. Scientists don’t know how the immune system will respond to the test.

This is the first of the COVID-19 vaccines to make it to 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.