What happened

Despite some rather good news with several coronavirus stocks on Monday, for the most part investors sold them off.

After an early morning price pop, bellwether Moderna (MRNA 3.28%) ended up sinking by over 6% on the day. Novavax (NVAX 2.95%), which fell 7%, could have been the poster child for the good news/bad stock price dynamic on the day. BioNTech (BNTX 0.55%) slid by more than 4%, even as the co-developer of its Comirnaty coronavirus vaccine, Pfizer (PFE 0.23%), crept up by nearly 3% on the day. 

Child wincing as he receives a vaccination shot.

Image source: Getty Images.

So what

The chief reason for these sell-offs on the day can be encapsulated in one word: omicron.

The latest news on the coronavirus variant is hardly encouraging. It is spreading rapidly in many areas of the world, including the Northeast U.S., where it has overwhelmed certain hospitals. This, despite the fact that the region has some of the highest vaccination rates in the country. Cancellations and tightened/renewed mask mandates are piling up as we head into the holidays.

With such worries in the background, it's little wonder that some otherwise encouraging news from these companies is being sidelined. For example, on Monday, Moderna announced that research shows that a booster shot of its mRNA-1273 vaccine notably raises the level of antibodies that can be used to battle omicron.

Novavax also had something very positive to report: One business day after its NVX-CoV2373 was granted a fresh Emergency Use Listing by the World Health Organization, the jab was awarded conditional marketing authorization by the 27-nation European Union. It is now the fifth vaccine authorized for use in that massive jurisdiction.

Now what

Fear was guiding investment decisions about coronavirus stocks on Monday, and as long as those alarming headlines spread across web pages and newspapers, that should continue. Perhaps investors are seeking shelter in certain defensive pharmaceutical titles, which might explain Pfizer's rise on the day. Either way, now is a nervy time to hold shares of biotechs active in the coronavirus fight.