'The main event': Moderna begins final phase of COVID-19 vaccine study

"This research study is something that I can do personally to benefit ... humanity," said one volunteer. Thousands more are needed.

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By Erika Edwards

The quest for a COVID-19 vaccine reached an important juncture Monday as Moderna Therapeutics began the first phase 3 trial of a COVID-19 vaccine candidate in the U.S.

Phase 3 is the final phase for a vaccine, so it is meant to answer the big question: Does the vaccine work to prevent COVID-19?

"This is the main event, if you will, in drug development," said Dr. Stephen Hoge, president of Moderna, a biotech company in Cambridge, Massachusetts.

Moderna partnered with the National Institute of Allergy and Infectious Diseases, or NAIAD, part of the National Institutes of Health, for its vaccine research.

"We urgently need a safe and effective preventive vaccine to ultimately control this pandemic," Dr. Anthony Fauci, the director of NIAID, said in a statement Monday.

As many as 30,000 volunteers will be recruited at nearly 100 research sites across the country in Moderna's phase 3 trial. Half of the participants will receive the vaccine, and the other half will receive a placebo. Neither the participants nor the researchers will know who gets the real vaccine and who gets the dummy shot.

Jon Penman, 24, of Omaha, Nebraska, has already signed up to participate.

Penman, who found out about the trial through an advertisement on Facebook, said he was motivated to volunteer because some of his family members are elderly and therefore at higher risk for complications of the coronavirus. He said he worries about their health "every day."

"This research study is something that I can do personally to benefit not only my family and my friends, but also humanity," Penman said.

Moderna was the first company in the U.S. to begin testing coronavirus vaccines in humans, giving its first dose March 16.

The company released results this month from its phase 1 trial, which included 45 adults. All of those participants developed antibodies to fight the virus at levels up to four times the amount found in patients who had recovered from the virus, the company said.

A preliminary assessment of how Moderna's phase 3 trial is progressing is expected after researchers record the first 50 cases of COVID-19 among the participants. That could be sometime this fall or winter.

"Having a safe and effective vaccine distributed by the end of 2020 is a stretch goal, but it's the right goal for the American people," Dr. Francis Collins, the director of the NIH, said in a statement.

The hope is that those who get the vaccine will be less likely to be among the first 50 cases to be diagnosed.

What these trials won't be able to answer, however, is how long immunity might last. "It's one of the great unknowns," Hoge said. Moderna's vaccine is likely to require two doses, but it's possible a third will be necessary.

Moderna is using a vaccine approach, called messenger RNA, that's never been marketed in the U.S. Instead of using bits of virus to provoke an immune response, it trains the immune system to target the spike protein found on the surface of the coronavirus.

The spike is what allows the virus to invade human cells. In theory, blocking the spike would mean people wouldn't become infected with the virus.

Other COVID-19 vaccines

Despite Moderna's early start, there won't be one "winner" in the pursuit of a COVID-19 vaccine. Multiple pharmaceutical companies will need to find a safe and effective vaccine to meet the global demand. And, like the flu shot, some vaccines may turn out to be better suited for certain populations, such as the elderly or people with compromised immune systems.

That's why the phase 3 trials will require thousands of participants from a variety of backgrounds.

"We are looking for a diverse population," said Dr. Brandon Essink, an investigator with Meridian Clinical Research, one of the sites participating in the Moderna trial.

Essink said his team is "looking for higher-risk patients, for more severe disease." That includes people of different ages and races, as well as those with comorbidities, such as heart disease, Type 2 diabetes and other risk factors.

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Worldwide, at least 150 vaccines are in development, but the vast majority are in the earliest stages of research.

Just four potential vaccines, including Moderna's, have advanced to phase 3 trials, according to the World Health Organization.

Pfizer is scheduled to join that group, as well, with plans to begin phase 3 trials this week. And the University of Oxford in England, in partnership with AstraZeneca, is expected to start its phase 3 studies within the next month.

One week ago, Oxford researchers announced results from their phase 1 trial showing that their vaccine candidate generated two strong immune responses: the production of both antibodies and T cells. The immune system makes antibodies in response to a virus so it can recognize it and fight it off a second time. T cells are also important, because they search for infected cells, attacking and killing them.

Johnson & Johnson announced Monday that it has also begun its first trials of a vaccine.

The Food and Drug Administration has said any COVID-19 vaccine would need to prevent illness or decrease the severity of the disease in 50 percent of people who receive it to be approved.

Ultimately, multiple vaccines will be needed to meet the global demand to stop or at least slow the pandemic.

"We're not putting all our bets on one vaccine candidate," said Dr. Walter Orenstein, associate director of the Emory Vaccine Center and a professor of infectious diseases at Emory University School of Medicine. Orenstein isn't involved in any phase 3 vaccine studies.

"This virus is circulating around the world," he said, so having several vaccines is "in our interest, not only to try and directly protect our own population, but to try to ensure that people around the world can get access to vaccines to minimize the virus reintroduction in the U.S."

Essink said, "It doesn't have to help 100 percent of people, but it has to help a majority."