The School of Medicine’s clinical trial for a COVID-19 vaccine provides encouraging evidence that the vaccine is safe and generates antibodies to neutralize the virus, according to preliminary results published in the New England Journal of Medicineon July 14.
“The fact that there were neutralizing antibodies that were identified with this study is an encouraging sign," said Evan Anderson, associate professor of pediatrics and medicine at the Emory University School of Medicine and principal investigator for the trial at Emory.
The mRNA-1273 vaccine, which was partially tested at Emory, is being manufactured by the biotechnology company Moderna which is based in Cambridge, Massachusetts. Moderna received $483 million from the federal government to develop the vaccine.
The vaccine consists of genetic material (mRNA) that codes for the spike protein region of the coronavirus. Upon entering the human body, the mRNA is translated to form the spike protein, which stimulates an immune response without causing severe sickness.
Phase 1 of the trial began on March 16 at the Kaiser Permanente Washington Health Research Institute in Seattle and the Hope Clinic and Emory Children’s Clinic at Emory University. This phase involved 45 participants between the ages 18 and 55, 17 of whom were participants at Emory. Participants were vaccinated a second time 29 days after the first injection. Blood samples of the participants were then tested to see if they generated antibodies.
According to Anderson, two different tests were used to detect whether the vaccinated subjects had neutralizing antibodies. One test used the live coronavirus and another less-hazardous test only used protein derivatives of the virus. Results of the trial show that all participants showed neutralizing activity after they received the second dose of the vaccine.
In addition to testing the neutralizing capacity of the generated immune response, blood samples of the participants were also compared to blood samples of individuals who had been diagnosed with and had recovered from the COVID-19.
“What we see here is that the antibody responses were really better than the antibody responses in most people that have recovered from COVID-19 infection,” Anderson said. “This is a benchmark that can be used. It is not a perfect benchmark, but it is at least a benchmark of the antibody response that can be produced.”
Participants in phase 1 of the trial will be monitored for a year to study whether the antibodies generated persist.
Phase 1 tested 25, 100 and 250 microgram doses. According to the preliminary results, certain adverse symptoms were common among participants, particularly after receiving the booster dose. These symptoms included headaches, fever, chills, body pain and nausea.
Anderson said that most of these symptoms disappeared around three days after receiving the vaccine. However, patients who received the highest dose experienced more severe symptoms.
“[Those who received] the highest dose of the vaccine, the 250 microgram dose, had … fevers and people really felt poorly, so that vaccine dose did not move further into the phase 2 and phase 3 of the clinical trials,” Anderson said. “The phase 1 study that we did was important in terms of doing what it was intended to do, that being identifying the right range of doses moving forward.”
Phase 2, which was not conducted at Emory, tested a 50 and 100 microgram dose, while phase 3 will only test the 100 microgram dose. Phase 3 of the trial will begin on July 27 at Emory, involve testing the vaccine on around 30,000 participants and be a double-blind, placebo-controlled study.
The manufacturing and testing of this vaccine has progressed at a faster pace than normal due to new technology, Andersen said.
“Most vaccines have focused on the use of a particular protein from the virus that we are trying to stimulate an immune response against,” Anderson said. For such vaccines, the protein is made in a laboratory and then purified, which are time intensive processes.
“For an mRNA vaccine it is a totally different technology,” Anderson said. “The mRNA is injected into the body and the body itself makes the proteins.”
Editor’s Note: Emory is currently seeking trial participants who are at high risk for COVID-19 due to their age, living conditions, working space and comorbidities. If you would like to participate, email ecc.vaccine@emory.edu or call 404-727-4044.
