Moderna Inc.’s covid-19 vaccine produced antibodies to the coronavirus in all patients tested in an initial safety trial, federal researchers said, clarifying a significant milestone as the United States continues to grapple with an increase in new infections.
The findings are likely to raise hopes that a vaccine can be marketed quickly. However, several patients in the trial experienced side effects, some of them serious. The vaccine will go into a late trial later this month that will likely determine if it is approved by US regulators.
The neutralizing antibody levels in the trial were equivalent to the upper half of what is seen in patients who become infected with the virus and recover, according to results published Tuesday in the New England Journal of Medicine.
While stimulating the production of neutralizing antibodies does not prove that a vaccine is effective, it is considered an important initial step in testing. Meanwhile, the reported side effects were not severe enough in most patients to prevent further testing, according to the report by researchers from the National Institute of Allergy and Infectious Diseases (NIAID).
Moderna’s shares gained 13.3% in trading after the market closed. The value of the shares has more than tripled this year, in the hope that her vaccine will get quick approval.
More than half of those who received half of the three doses suffered mild to moderate fatigue, chills, headache, and muscle pain. Furthermore, 40% of people in the medium dose group experienced fever after the second vaccination. Three of the 14 patients who received the highest dose experienced serious side effects, but that dose is not being used in larger trials.
“Man, there are a lot of adverse events,” said Tony Moody, a physician 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 antibody levels produced were “really encouraging.”
If the researchers are measuring the right thing, the vaccine should work, he said, noting that this can only be proven in large trials.
The news of the vaccine came as the pandemic continues to thrive across the United States. Cases across the country rose to 3.4 million on Tuesday, according to data compiled by Johns Hopkins University and Bloomberg News. More than 136,117 Americans have died.
NIAID director Anthony Fauci called Moderna’s data “really quite promising” in a telephone interview after the report’s release. He said the observed side effects were not alarming and were typical of the effects seen with other vaccines.
“The good news is that this vaccine induced antibodies,” said Fauci. “Not just any type of antibody, but neutralizing antibody.”
Moderna’s initial results are from the first group of 45 patients who received the vaccine. He evaluated three doses of the vaccine that were administered in a two-injection regimen. The median dose of this initial trial will be used in a large, modern-stage, modern-vaccine vaccine trial, called mRNA-1273, to begin on July 27.
In the trial, participants received two doses of the vaccine 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 it.
But the 42 people who received both scheduled doses of the vaccine raised antibodies capable of neutralizing the coronavirus, according to the study results. The final stage of the trial will compare the vaccine with placebo vaccines in 30,000 healthy people at high risk of contracting the coronavirus.
A significant limitation of the data is that only the first 45 patients are included in the study, all 18 to 55 years of age. Results of a second part of the phase 1 trial that included people older than this, a demographic key to any covid-19 vaccine, given the high mortality rate in older patients, are not yet available.