Moderna chairman Noubar Afeyan
© Getty Images for Aurora HumanitaModerna chairman Noubar Afeyan, whose estimated net worth is $3.7 billion, is ranked 212 on the Forbes' 400 list in 2021.
The success of Moderna's COVID-19 vaccine has minted three new billionaires who had early stakes in the biotech startup, leading to their debut on this year's Forbes list of the 400 richest people in the US.

Moderna co-founder and chairman Noubar Afeyan along with fellow co-founder and Massachusetts Institute of Technology professor Robert Langer both made the list, with estimated net worths of $3.7 billion and $3.5 billion, respectively.

Timothy Springer, a Harvard Medical School professor and early Moderna investor, also debuted on the list with a net worth of $4.4 billion, according to Forbes.

Since Moderna became the second company to win an emergency use authorization for its COVID-19 vaccine, more than 152.3 million doses have been administered, according to data from the Centers for Disease Control and Prevention.

The company has previously said it expects to make at least $19.2 billion in sales of its COVID-19 vaccine.

Moderna's successful development of the vaccine propelled it out of the world of biotech startup obscurity and landed huge gains for shareholders.

The stock has fallen off its peak in recent weeks, but it's still up more than 189 percent since Jan. 1, and over 300 percent higher compared with a year ago.

Since its initial public offering at $22 per share in 2018, the company's stock is up more than 1,200 percent. It was last seen trading at $297.50 a share.

The company's now valued at more than $120 billion, larger than beverage giant Diageo and jet engine maker General Electric.

Timothy Springer, an early investor in Moderna, sits in the 176th spot — ahead of Afeyan and Langer.

It's a massive market valuation for a firm whose revenue is made up of just one product, but investors are betting that Moderna can leverage its expertise in mRNA vaccines to address — and cash in on — other major public health challenges such as cancer and malaria.

But already, the stock has begun to slip. Pharmaceutical giant Merck last week announced that it's seeking emergency authorization from US regulators for its oral antiviral treatment for COVID-19 after the experimental drug showed "compelling results" in clinical trials.

The news sparked hope that the world could soon have another easy treatment for COVID-19, but it hurt Moderna investors, with the stock falling nearly 24 percent since the announcement.

The stock was also hurt Wednesday after Sweden and Denmark announced a pause on the use of Moderna's COVID-19 vaccine for young people after reports of possible rare cardiovascular side effects.