The results should increase the hope that a vaccine can be brought to market quickly. However, a number of patients in the trial had side effects, some of which were serious. The vaccine will undergo a much larger advanced stage trial later this month, which should determine whether it is approved by US regulatory authorities.
According to results published Tuesday in the New England Journal of Medicine, the levels of neutralizing antibodies in the test produced were equivalent to the upper half of what is seen in patients infected with the virus and recovering.
Although stimulating the production of neutralizing antibodies does not prove that a vaccine will be effective, it is considered an important early step in testing. Meanwhile, the reported side effects were not severe enough in the majority of patients to preclude further testing, according to the report from researchers at the National Institute of Allergies and Infectious Diseases.
Moderna shares gained 13.3% in trade after the market closed. The stock has more than tripled in value this year, hoping that its vaccine will get quick approval.
More than half of those who received the middle of three doses suffered from mild to moderate fatigue, chills, headache and muscle pain. In addition, 40% of people in the mid-dose group had a fever after the second vaccination. Three of the 14 patients who received the highest dose experienced serious side effects, but this dose is not used in larger trials.
“Man, that’s a lot of adverse events,” said Tony Moody, a doctor and researcher at the Duke Human Vaccine Institute. He said it would be “unusual” for a vaccine to have this rate of side effects. On the positive side, he said the levels of antibodies produced were “really encouraging”.
If researchers measure the right thing, the vaccine should work, he said, noting that this can only be proven in large trials.
News of the vaccine came as the pandemic continued to spread across the United States. Cases nationwide increased Tuesday to 3.4 million, according to data collected by Johns Hopkins University and Bloomberg News. More than 136,117 Americans died.
While some states that have suffered this spring have managed to stifle their epidemics, fierce hot spots are breaking out in the solar belt. Arizona reported 4,273 new cases on Tuesday, the most in 11 days. Texas reported a daily record of 10,745. And Florida deaths increased by a record 132.
Anthony Fauci, director of NIAID, called Moderna’s data “very promising” in a telephone interview after the report was released. He said the side effects observed were not alarming and were typical of the effects seen with other vaccines.
“The good news is that this vaccine has produced antibodies,” said Fauci. “Not just any type of antibody, but neutralizing antibodies. “
The first results of Moderna come from the first group of 45 patients who received the vaccine. He evaluated three doses of the vaccine which were administered in two injections. The average dose from this initial trial will be used in a large final trial of the Moderna vaccine, called mRNA-1273, which is scheduled to start on July 27.
In the trial, participants received two shots 28 days apart. After the first dose, all participants generated antibodies that bound to the coronavirus, but most did not yet produce antibodies capable of neutralizing the virus.
But the 42 people who received the two planned doses of the vaccine generated antibodies capable of neutralizing the coronavirus, according to the results of the study. The final phase trial will compare the vaccine to placebo injections in 30,000 healthy people at high risk of contracting the coronavirus.
An important limitation of the data is that it only includes data from the first 45 patients in the study, all aged 18 to 55 years. Results from a second part of the phase 1 trial that included older people – a demographic key to any Covid-19 vaccine, given the high mortality rate in older patients – are not yet available.
William Haseltine, a former Harvard Medical School researcher who chairs Access Health International, said the levels of neutralizing antibodies produced were “respectable” and perhaps protective. But he said that “the jury is out” on the safety of the vaccine.
Unlike traditional vaccines, which inject a weakened or inactivated virus or a piece of virus to trigger an immune response, the Moderna product uses genetic material called messenger RNA to cause cells to produce the advanced protein of the coronavirus. The goal is to produce antibodies against the virus that protect against the disease when someone is subsequently exposed to the coronavirus.
The vaccine “clearly worked in that the antibodies against the tip
proteins were generated, including antibodies that had the ability to neutralize viruses, “said Paula Cannon, professor of microbiology at the USC Keck School of Medicine. A key question will be how long will the antibodies last before they start to decline, she said.
Initial results from the Phase 1 trial are largely consistent with Moderna’s first-line results published in a press release in May, but provide more detail on the levels of antibodies produced and the side effects seen.
Moderna was criticized at the time by some scientists for publishing a press release describing positive results that temporarily boosted the company’s stock price, but included some numbers that would allow scientists to interpret the data.
The government-sponsored trial was conducted by Lisa A. Jackson of the Kaiser Permanente Washington Health Research Institute in Seattle, NIAID said in its statement. Emory University of Atlanta also enrolled trial participants.
(Adds comments from Fauci from the 11th paragraph, details on the trial in the 13th and 14th paragraphs.)
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Video: Positive result for the first trial of the American COVID-19 vaccine (Associated Press)