Potential vaccines for COVID-19 are working their way through the clinical trial process at lightning speed and in a very nontraditional fashion as the virus pulses through communities throughout the country.
The leading vaccine candidate, developed by Moderna, is entering its third clinical trial phase, and the U.S. biotechnology company is seeking out about 30,000 volunteers for the blind trial which will give half the candidates vaccines and the other half a placebo. The trial began in late July and is still accepting volunteers. The goal of the Phase 3 trial is to evaluate safety as well as see if the vaccine can prevent COVID-19 after two doses.
The Moderna vaccine trial was tested first in humans for safety as early as March 2020, and some Phase 1 participants were from Seattle at the Kaiser Permanente site. That site will be used in Phase 3 as well, and areas around the United States that have high prevalence of COVID-19 or are considered hot spots are going to be targeted for the third phase.
So far, clinical trials for Moderna’s COVID-19 vaccine have produced only light symptoms in trial participants, and the vaccine is also showing promising results in tests on mice and monkeys.
The mNRA-12743 vaccine induced high antibody levels in nonhuman primates and protected the monkeys’ upper and lower airways from the virus, a recent study of the vaccine candidate found. Similarly, when the vaccine candidate was tested in mice, they produced antibodies and were protected against infection in their noses and lungs.
The goal of a COVID-19 vaccination is to initiate an immune response in a person’s body, which produces antibodies that can protect the body and potentially fight off an infection. Some vaccine trials are finding that a vaccine also produces T-cell responses as well. The efficacy of a vaccine, or how long (or what amount of) antibodies can protect you from the virus and to what effect, is still being studied, and is, in a way, the million-dollar question.
“Everyone is aiming for sterilizing immunity, but the question is do we need it?” Jesse Erasmus, postdoctoral fellow at the University of Washington School of Medicine, said. “It’s unknown.”
The vaccine developed by Moderna is a two-dose vaccine, with 28 days between doses. This time lapse could present a challenge in rolling out the vaccine, especially if people are not immune after the first dose. Several researchers are working to produce a vaccine, however, including Erasmus. Last week, Spokane County Health Officer Dr. Bob Lutz estimated that there are about 180 vaccine candidates being researched worldwide.
Erasmus started his research in mice first, as is traditional in typical vaccine trials. Erasmus is also using a unique platform for his vaccine which has not been tested in humans.
Some vaccine candidates, like Moderna’s, are using platforms that have been used in humans previously, which is why they had such a head start.
Erasmus had already developed a vaccine platform as a part of his dissertation at the University of Texas, where he focused on what are called Alphaviruses.
The first step for vaccine research, Erasmus said, is to ensure that your vaccine is safe.
“We don’t care about if the vaccine will work at first, we care if it’s safe and that allows us to move onto the next step,” he said.
Erasmus first tested his replica RNA vaccine on mice, then monkeys. He found that his RepRNA vaccine was not only safe but also produced robust immune responses in both, including in older mice, which is a promising result. He cautioned that animal trials are just that, tests on animals, not humans.
“Mice do an okay job of mimicking the human immune system, but mice exaggerate and monkeys lie,” he said. “So the immune response we see in a mouse will be significantly better than what we see in a human and what we see in a monkey may not be relevant to what we see in a human.”
Having cleared the lab phase for his Alphavirus-derived repRNA vaccine, Erasmus then passed his work off to a company, where they can initiate a toxicology study, to ensure that it is safe, and then onto a human clinical study. Erasmus said that working “on the bench” or in the lab with animals is a lot cheaper and efficient for studying vaccines at first.
“We can move much faster, more efficiently and it’s a lot cheaper,” he said.
Erasmus’ research is now in the hands of HDT Bio, a biological research company based in Seattle, which has begun to conduct a toxicology study first, Erasmus said. Afterwards, the vaccine will move into human clinical trials.
Erasmus plans to stay in the lab and continue to track and monitor the immune responses of the mice and monkeys he tested the vaccine candidate on. He recently took blood samples at the 120-day mark.
“We’re continuing to sample every month now and hoping to evaluate longevity to see how long immune responses will last,” he said.
The UW fellow also hopes that his vaccine candidate will be able to produce a lower dose and a single dose, which would differentiate it from Moderna’s two-step vaccine.
At the earliest, national health officials are optimistic about seeing a vaccine candidate be viable by the end of 2020. One official called that a “stretch goal.”
Realistically, Phase 3 of the Moderna vaccine candidate trial will take some time as researchers recruit the 30,000 people and vaccinate them with their first dose. Then it will take more than 28 days and a follow-up with each volunteer to get their second dose. Researchers will then continue to track symptoms after participants have received both doses. From there, the FDA can grant emergency use authorization for a vaccine to go to the market, given that it meets safety protocols and standards.
“There might be multiple candidates and multiple vaccines available through emergency use authorization,” Lutz said last week, noting that he believes authorization will only be granted after rigorous studies for safety and efficacy have been completed.
Lutz said he was cautiously optimistic, as are national health officials, that there might be a viable vaccine candidate by winter 2020 or spring 2021. Despite the rushed research process, Lutz believes that what eventually comes to the market will be safe.
“I think the rigor of the safety issues are going to be significant,” he said.
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