Moderna’s vaccine profits propel three new names onto Forbes’s list of the 400 richest Americans.

The financial windfall at Moderna, the biotech company behind one of the three federally cleared Covid-19 vaccines, has propelled three new names onto Forbes magazine’s list of the 400 richest people in the United States.

Using stock prices and exchange rates from early September, the magazine’s list added Noubar Afeyan, Moderna’s chairman and co-founder; Robert Langer, a Massachusetts Institute of Technology professor and Moderna co-founder; and Timothy Springer, a Harvard Medical School professor and early investor in the company. The stated net worth of each was more than $3.5 billion.

A representative for Moderna did not immediately respond to a request for comment.

The coronavirus pandemic has been an economic catastrophe for much of the country, but the richest have done well, Forbes noted when it published the list on Tuesday: The 400 people included saw their collective wealth increase 40 percent during the last year.

Moderna makes one of the three vaccines authorized for use in the United States. Headquartered in Cambridge, Mass., the company was founded in 2010 with the goal of bringing RNA-related products to market. Its only commercial product is the Covid vaccine, for which the U.S. government provided $1 billion to support design and testing. With countries around the world buying as much vaccine as possible, Moderna’s valuation topped $100 billion this summer.

The company’s stock price Wednesday was more than four times its value at this time last year, even though its share prices have been slipping, with a major drop of about 18 percent in the past week alone. Most of that drop came on Friday, after the pharmaceutical giant Merck said that its new pill to treat Covid-19 reduced the risk of hospitalization and death by about 50 percent. Merck plans to seek federal emergency use authorization for the antiviral pills.

That drop significantly reduced the worth of the three Moderna billionaires. Dr. Springer was No. 176 on the list and worth $5.9 billion when the Forbes calculations were made on Sept. 3, a figure that had dropped to $4.6 billion by Wednesday. The reported worth of Mr. Afeyan, No. 212, fell from $5 billion to $3.8 billion. And the wealth of Dr. Langer, No. 222, slipped from $4.9 billion to $3.7 billion, Forbes said.

Moderna’s vaccine, which is built around messenger RNA, as is the one developed by Pfizer-BioNTech, was authorized for emergency use for people 18 and older by the Food and Drug Administration last December. Moderna submitted its vaccine for an emergency use authorization in 12- to 17-year-olds in June and for full federal approval in August; regulators’ decisions are pending.

More than 283 million doses of Moderna’s vaccine have been administered in almost 40 countries that reported their vaccine distribution data to the Our World in Data Project at Oxford University, and Moderna’s revenues have ballooned since the vaccine saw widespread use.

In its most recent financial statement Moderna said that its total revenues were $4.4 billion for the three months ending June 30, 2021, compared to $67 million for the same period in 2020. Net income for the six months ending on June 30, 2021, was $4 billion, compared to a net loss of $241 million during the same period in 2020.