Researchers in Seattle have begun recruiting healthy volunteers to participate in a clinical trial for an experimental COVID-19 vaccine, according to news reports.

The vaccine, developed by the biotechnology company Moderna Therapeutics, was initially sent to the National Institute of Allergy and Infectious Diseases (NIAID) in Maryland on Feb. 24, according to The Wall Street Journal . The agency anticipates launching a clinical trial by the end of April and will sponsor the Kaiser Permanente Washington Health Research Institute to conduct the testing, NIAID Director Anthony Fauci told The Wall Street Journal.

Forty-five healthy volunteers between the ages of 18 and 55 will be enrolled in the initial trial, which aims to determine whether the vaccine triggers an immune response, and whether the given dose causes adverse side effects, according to a description on ClinicalTrials.gov .

The vaccine does not contain the virus that triggers COVID-19, called SARS-CoV-2, and cannot cause infection, according to a report by Kaiser Permanente . Unlike vaccines developed for other viruses, such as measles, this new vaccine does not utilize a weak or dead virus as its base. Instead, the vaccine contains a short segment of genetic material called messenger RNA, or mRNA, generated in a laboratory. In a typical cell, mRNA encodes instructions for building different proteins.

Related: 10 deadly diseases that hopped across species

The artificial mRNA prompts cells to build a protein found on the surface of the virus, according to the Kaiser Permanente report. A person's immune system should react to this new protein by building up an arsenal of antibodies that target and latch onto this protein, tagging the virus for elimination. Then, the mRNA should break down and be eliminated by the body, leaving the vaccinated person better prepared to fight off SARS-CoV-2, should they ever encounter it.

Designing the vaccine to work in this way allowed Moderna to fast-track the development process, as the company did not need to isolate and modify live samples of SARS-CoV-2 as it would for a more conventional vaccine, according to Kaiser Permanente.

Volunteers will receive two injections of the vaccine in the upper arm, with a 28-day gap between doses. The 45 participants will be split into three groups, with each group receiving a different dose of the vaccine. Volunteers will be asked to attend 11 in-person study visits over the course of the 14-month study and will receive $100 for each appointment they attend, totaling up to $1,100 by the end.

Following this initial safety trial, the vaccine's effectiveness must be tested in several subsequent trials in larger groups of people before being distributed widely. Meanwhile, researchers around the world will continue to work on viable treatments to help people who contract the virus. For now, patients with COVID-19 will receive supportive care to address symptoms of the disease, Live Science previously reported .

Although this advance in vaccine development is encouraging, earlier this week, U.S. health officials noted that they can't guarantee that a COVID-19 vaccine will be affordable.

"We would want to ensure that we work to make it affordable, but we can't control that price because we need the private sector to invest," Health and Human Services Secretary Alex Azar told the House Energy and Commerce Committee Wednesday (March 4), according to Market Watch . "The priority is to get vaccines and therapeutics, and price controls won't get us there."

However, Moderna Therapeutics CEO Stéphane Bancel has stated that the company's vaccine should be affordable.

"We are highly aware this is a public-health issue, and so we will be very thoughtful about setting a price if this product gets to approval," Bancel told Business Insider . "There is no world, I think, where we would contemplate to price this higher than other respiratory virus vaccines."

Originally published on Live Science .