An infectious disease expert cautioned against the hasty interpretation of Moderna’s interim results from the phase-1 trial of an experimental Covid-19 vaccine.
Professor Kim Woo-ju of the Infectious Disease Department of Korea University Guro Hospital made the warning on a YouTube live program on Thursday to analyze the interim results of Moderna’s phase-1 study on mRNA-1273, a potential Covid-19 vaccine.
Moderna had announced that its vaccine candidate helped build immunity against Covid-19, sparking a debate over the data’s credibility
A phase-1 trial on a vaccine aims to verify the safety and immunogenicity of the vaccine in healthy people. Normally, a principal investigator reports the final results to a sponsor (developer) and the regulator after the completion of the phase-1 study, Kim said. By the time a paper is announced, the results are released to the public.
However, it was the developer Moderna, not the principal investigator, that disclosed interim results, not final ones, and this was unusual, Kim noted.
“I think the company may have made such unprecedented announcement, given that everyone is desperately waiting for the vaccine clinical results with the worldwide spread of Covid-19,” he said. “However, it was not easy to understand the results because they were presented in the form of a press release rather than the usual form.”
Kim explained that the phase-1 trial on mRNA-1273 divided 45 healthy adults aged between 18 and 55 into three groups of 15 with different dosing -- 25µg, 100µg, and 250µg group. The 25µg and 100µg group received the vaccine two times with a four-week interval, and the 250µg group received once.
"Since Covid-9 is a new virus, it is not possible to form enough antibodies with a single vaccination," said Kim. "The study evaluated the vaccine's immunogenicity by collecting blood in the second week of the vaccination when the antibody titer rises to the maximum."
The results showed that all three groups formed antibodies on day 15 after the first administration of the vaccine candidate. The 15 people in the 25µg group developed antibodies on day 43 (the second week of the last vaccination), and 10 in the 100µg group, also on day 43.
In terms of safety, the results were positive, Kim said. Only one in the 100µg group reported injection site reactions and tenderness of Grade 3 and others did not have any problem, he said.
Kim noted that Moderna mentioned only antibody formation and did not disclose any information about antibody titers or persistence, which is why the issue got controversial.
“From this data alone, it is not possible to tell how much antibodies have been formed and how long they will last,” he said. Moreover, there were only eight people’s results that showed the neutralizing antibodies that guard people against the virus, and results from 37 people are unknown. “Critics say it was too early to announce the interim results,” Kim said.
Moderna said four in the 25µg group and four in the 100µg had neutralizing antibodies on Day 43. The company said the formation of neutralizing antibodies was found in all eight people analyzed.
However, it did not reveal how many neutralizing antibodies were formed.
Moderna’s latest study recruited a small number of 45 people, and the study results do not guarantee the safety of the vaccination for millions of people, Kim went on to say.
The company’s interim data alone do not present any effect of immunogenicity, either, he added.
“The U.S. government is pressuring companies to accelerate vaccine development but clinical studies on a vaccine are not something you should rush,” Kim emphasized.
Moderna’s shares took a nosedive after the media questioned the clinical clarity of its data and raised suspicions on possible ties to the Trump administration.
Media reports said that Moncef Slaoui, the new chief scientist of the White House’s initiative to develop a Covid-19 vaccine, was a former executive of Moderna and had a large volume of stock options. He sold his shares after Moderna’s stocks spiked, following the announcement of the interim study results, which fueled the concern for conflicts of interest.
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