Skip to main content

A sign marks the headquarters of Moderna Therapeutics, which is developing a vaccine against COVID-19, in Cambridge, Massachusetts, U.S., May 18, 2020. Moderna’s technology, involving genetic material from the virus called mRNA, is relatively new and has yet to produce any approved vaccine.Brian Snyder/Reuters

The first coronavirus vaccine to be tested in people appears to be safe and able to stimulate an immune response against the virus, its manufacturer, Moderna, announced Monday.

The findings are based on results from the first eight people who each received two doses of the experimental vaccine, starting in March.

Those people, healthy volunteers ages 18 to 55, made antibodies that were then tested in infected cells in the lab and were able to stop the virus from replicating – the key requirement for an effective vaccine. The levels of those so-called neutralizing antibodies matched or exceeded the levels found in patients who had recovered after contracting the virus in the community.

The findings do not prove the vaccine works. Only larger, longer studies can determine whether it can actually prevent people in the real world from getting sick. Moderna’s technology, involving genetic material from the virus called mRNA, is relatively new and has yet to produce any approved vaccine.

Moderna produced the vaccine in collaboration with the National Institute of Allergy and Infectious Diseases, the institute led by Dr. Anthony Fauci, which has been leading the clinical trials.

The news helped buoy Wall Street, rallying the markets. In recent months, Moderna’s stock has soared as it pursued a vaccine, and it was up more than 25% by midafternoon Monday.

Dozens of other companies and universities are also rushing to create coronavirus vaccines.

At the same time, there is widespread concern that haste could compromise safety, resulting in a vaccine that does not work or even harms patients. Vaccines have generally taken years, sometimes a decade or more, to reach the market.

Moderna’s early stage of testing, phase one, is continuing.

Moderna has said it is proceeding on an accelerated timetable, with the second phase involving 600 people to begin soon, and a third phase to begin in July involving thousands of healthy people. The 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, said Dr. Tal Zaks, Moderna’s chief medical officer. How many doses might be ready is not clear, but Zaks said, “We’re doing our best to make it as many millions as possible.”

Sign up for the Coronavirus Update newsletter to read the day’s essential coronavirus news, features and explainers written by Globe reporters and editors.