Food and Drug Administration gave Moderna the go-ahead for the second phase earlier this month.
If those trials go well, a vaccine could become available for widespread use by the end of this year or early 2021, Dr. Tal Zaks, Moderna’s chief medical officer, said in an interview. How many doses might be ready is not clear, but Dr. Zaks said, “We’re doing our best to make it as many millions as possible.”
There is no proven treatment or vaccine against the coronavirus at this time. Dozens of companies in the United States, Europe and China are racing to produce vaccines, using different methods. Some use the same technology as Moderna, which involves a segment of genetic material from the virus called messenger RNA, or mRNA.
Moderna said that additional tests in mice that were vaccinated and then infected found that the vaccine could prevent the virus from replicating in their lungs, and that the animals had levels of neutralizing antibodies comparable to those in the people who had received the vaccine.
Three doses of the vaccine were tested: low, medium and high. These initial results are based on tests of the low and medium doses. The only adverse effect at those doses was redness and soreness in one patient’s arm where the shot was given.
But at the highest dose, three patients had fever, muscles and headaches, Dr. Zaks said, adding that the symptoms went away after a day.
But the high dose is being eliminated from future studies, not so much because of the side effects, but because the lower doses appeared to work so well that the high dose is not needed.
“The lower the dose, the more vaccine we’ll be able to make,” Dr. Zaks said.
Moderna’s stock has soared in recent months, and was up more than 23 percent on Monday morning after releasing the preliminary results.
