By Mackenzie Tatananni

New York City officials have confirmed the first case of a more severe strain case of mpox. While the risk of transmission remains low, shares of certain vaccine-makers might be worth a second look.

Mpox, formerly known as monkeypox, is a viral infection characterized by a flu-like fever and rash that can last weeks. It's caused by a virus in the same family as smallpox, though it's less contagious and less severe.

Bavarian Nordic is the biggest player to keep an eye on. With a market capitalization of just over $2 billion and shares that trade over the counter in the U.S., the name might not be widely known to investors outside the biotechnology space.

The company manufactures one of only two approved mpox vaccines in the U.S. Because mpox is a viral infection, the answer isn't as simple as taking antibiotics to treat it. However, as is the case with Covid, people can vaccinate to build their body's natural resistance to it.

Bavarian Nordic's product is sold under the name Jynneos and is administered as a two-dose series, four weeks apart. The Food and Drug Administration issued an emergency use authorization for Jynneos back in August 2022 amid the last known outbreak of mpox in the U.S., which concerned a different, less severe strain called clade II.

While Bavarian Nordic is headquartered in Europe, as the name suggests, the U.S. is by far its largest market. The company's U.S. operations brought in the bulk of revenue at $2.7 billion in 2025.

Another player to watch is Emergent Biosolutions, the small-cap drugmaker behind ACAM2000, the other FDA-sanctioned vaccine. ACAM2000 is also approved for the prevention of smallpox in individuals determined to be at high risk for infection.

SIGA Technologies is another name to keep an eye on. SIGA's lead candidate to treat mpox, tecovirimat, is currently only cleared for patients with smallpox. An initial analysis of data from two randomized clinical studies showed that tecovirimat was safe, but doesn't reduce the time to resolution of mpox lesions.

However, the product is available outside clinical trials through the FDA's expanded access pathway -- often referred to as "compassionate use" in patients with immunocompromised conditions or severe disease.

Mpox has yet to enter a true outbreak just yet. Since November 2024, there have been 12 reported cases of clade I monkeypox in the U.S., while clade II -- the more severe strain -- is "circulating at low levels," per the Centers for Disease Control and Prevention.

Write to Mackenzie Tatananni at mackenzie.tatananni@barrons.com

This content was created by Barron's, which is operated by Dow Jones & Co. Barron's is published independently from Dow Jones Newswires and The Wall Street Journal.

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March 17, 2026 12:49 ET (16:49 GMT)

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