What happened

Most COVID-19 vaccine stocks are having a terrible end to the week. Shares of Moderna (NASDAQ:MRNA) are off by 3.4%; Novavax (NASDAQ:NVAX) is down 5.1%; and Ocugen's (NASDAQ:OCGN) stock is in the red by a jaw-dropping 13.3%, all as of 3:34 p.m. EDT Friday. 

While it might be easy to blame the possibility of forthcoming home treatments for moderate COVID-19 cases for this across-the-board drop, the real reason(s) are likely more complex. The U.S. Food and Drug Administration (FDA) might delay the decision on Moderna's jab for adolescents due to safety issues, according to a report from the Wall Street Journal. Novavax's COVID-19 vaccine continues to fall behind the leaders in the space -- possibly knocking down its peak sales by a significant amount. And Ocugen, through its Indian partner, has yet to hear from either the World Health Organization or the FDA about their vaccine candidate.

Researcher inspecting vials of COVID-19 vaccines.

Image source: Getty Images.

So what

The COVID-19 vaccine market might evaporate -- or at least shrink dramatically -- far faster than most anticipate. That's bad news for the revenue prospects for Moderna, Novavax, and Ocugen. Orally administered antiviral pills from a host of companies could be available early to mid-2022; cases are starting to subside in key developed markets, which suggests that herd immunity may be close within some populations; and other vaccine makers like Pfizer/BioNTech and Johnson & Johnson may be able to cover the remaining demand in the most lucrative of markets. Viewed this way, it's not altogether surprising investors are rethinking their positions in some of these COVID-19 vaccine companies today. 

Now what

Shareholders may want to take a breather, however. Viral pandemics have an odd way of persisting for years -- mainly through mutations that make them harder to contain via first-generation vaccines.

What's more, there's no guarantee that these oral antiviral pills will make their way to the market quickly. Safety concerns are already holding up an Emergency Use Authorization for Merck and partner Ridgeback Biotherapeutics' oral medication. As a result, the FDA has decided to convene a public hearing later this year to vet the drug's risks versus its benefits. Competing therapies from Pfizer and Atea Pharmaceuticals won't yield top-line data for several more months.  

All told, this is a worrying time for shareholders of high-flying COVID-19 vaccine makers like Moderna, Novavax, and Ocugen. The future is highly uncertain, after all. But panic selling probably isn't the best idea. Instead, the wisest course of action is likely to sit and wait for the market to mature, and keep an eye on how the pandemic evolves. In short, there could be a tremendous need for a variety of mitigation strategies -- including several different vaccines -- for a long time to come. Stay tuned.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.