Moderna Coronavirus Vaccine Shows Promise in Key Early Trial

Moderna Inc.’s Covid-19 vaccine produced antibodies to the coronavirus in all patients tested in an initial safety trial, federal researchers said, clearing an important milestone as the U.S. continues to grapple with a surge in new infections.

The findings are likely to increase hopes that a vaccine can be brought to market quickly. However, a number of patients in the trial experienced side effects, some of them severe. The vaccine will move into a much larger late-stage trial later this month that’s likely to determine whether it’s approved by U.S. regulators.

The neutralizing antibody levels in the trial produced were equivalent to the upper half of what’s seen in patients who get infected with the virus and recover, according to the results published Tuesday in the New England Journal of Medicine.

While stimulating production of neutralizing antibodies doesn’t prove a vaccine will be effective, it’s considered an important early step in testing. Meanwhile, the side effects reported weren’t severe enough in the majority of patients to preclude further testing, according to the report by researchers from the National Institute of Allergy and Infectious Diseases.

Moderna’s shares gained 13.3% in trading after the market closed. The stock has more than tripled in value this year on hopes that its vaccine will gain rapid approval.

More than half of those who got the middle of three doses suffered mild to moderate fatigue, chills, headache and muscle pain. Also, 40% of people in the middle-dose group experienced a fever after the second vaccination. Three of 14 patients given the highest dose experienced severe side effects, but that dose is not being used in larger trials.

“Man, that is 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 plus side, he said that the antibody levels produced were “really encouraging.”

If researchers are measuring the right thing, the vaccine should work, he said, noting that this can only be proved in large trials.

The vaccine news came as the pandemic continued thriving throughout the U.S. Cases nationwide increased Tuesday to 3.4 million, according to data collected by Johns Hopkins University and Bloomberg News. More than 136,117 Americans have died.

While some states that suffered this spring have managed to quell their outbreaks, fierce hot spots are breaking out in the Sun Belt. On Tuesday, Arizona reported 4,273 new cases, the most in 11 days. Texas reported a daily record of 10,745. And Florida deaths rose by a record 132.

Anthony Fauci, the NIAID director, called the Moderna data “really quite promising” in a telephone interview after the report was released. He said the side effects seen were not alarming and were typical of effects seen with other vaccines.

“The good news is that this vaccine induced antibodies,” Fauci said. “Not just any kind of antibodies, but neutralizing antibodies.”

Moderna’s initial results are from the first group of 45 patients who received the vaccine. It evaluated three doses of the vaccine that were given in a two-shot regimen. The middle dose from this initial trial will be used in a large final-stage trial of the Moderna vaccine, called mRNA-1273, that is slated to begin on July 27th.

In the trial, participants received two shots of the vaccine 28 days apart. After the first dose, all of the participants generated antibodies that bound to the coronavirus, but most did not yet produce antibodies capable of neutralizing the virus.

But all 42 people who got both scheduled doses of the vaccine generated antibodies capable of neutralizing the coronavirus, according to the study results. The final stage trial will compare the vaccine to placebo shots in 30,000 healthy people at high risk of coming down with the coronavirus.

One significant limitation of the data is it only includes data from the first 45 patients in the study, all of whom were from age 18 to 55. Results from a second portion of the phase 1 trial that included people older than this -- a key demographic for any Covid-19 vaccine, given the high death rate in older patients -- are not available yet.

William Haseltine, a former Harvard Medical School researcher who chairs Access Health International, said the levels of neutralizing antibodies produced were “respectable” and possibly protective. But he said “the jury is out” on safety of the vaccine.

Unlike traditional vaccines, which inject a weakened or inactivated virus or a piece of a virus to trigger an immune response, the Moderna product uses genetic material called messenger RNA to cause cells to produce the coronavirus spike protein. The goal is to produce antibodies to the virus that protect against the disease when someone is later exposed to the coronavirus.

The vaccine “clearly worked in that antibodies against the spike

protein were generated, including antibodies that had virus neutralizing capability,” said Paula Cannon, professor of microbiology at Keck School of Medicine of USC. A key question will be how long will the antibodies last before they start to wane, she said.

The initial findings from the Phase 1 trial are largely in line with top-line results Moderna published in a press release in May, but provide more details on the antibody levels produced and side-effects that were seen.

At the time, Moderna was criticized by some scientists for putting out a release describing positive results that temporarily drove up the company’s stock price, but included few numbers that would allow scientists to interpret the data.

The government-sponsored trial was led by Lisa A. Jackson of Kaiser Permanente Washington Health Research Institute in Seattle, the NIAID said in its statement. Emory University in Atlanta also enrolled participants in the trial.