What happened

Shares of a clutch of healthcare companies involved directly or tangentially in the fight against the coronavirus were doing very well on Monday. Moderna (NASDAQ:MRNA), for one, was up by nearly 10% in midafternoon trading, while Co-Diagnostics (NASDAQ:CODX) was trailing close behind. 

Meanwhile, both Novavax (NASDAQ:NVAX) and Vaxart (NASDAQ:VXRT) were outpacing that pair, with 16% and 11% gains, respectively. BioNTech (NASDAQ:BNTX) was a relative laggard, rising "only" 5.7%.

Man receiving a vaccination shot.

Image source: Getty Images.

So what

The key reason for these increases is simple: Because of its powerful delta variant, the coronavirus is very much on the rise again. According to New York Times data, statistics from Sunday indicate the 14-day change in new cases in the U.S. was a worrying 140% increase, with fatalities rising 33%.

So the need for a harder and wider vaccine push is obvious; such a move would clearly benefit both Moderna and BioNTech. These companies (including BioNTech partner Pfizer) provide two of only three coronavirus vaccines authorized by the Food and Drug Administration. It should also help Co-Diagnostics, which is a high-profile maker of a COVID-19 testing product.

Now what

If the coronavirus surge continues, it's very possible we'll face an "all hands on deck," situation with vaccines. Perhaps the ones being developed by vaccine-focused biotechs Novavax and Vaxart will be authorized by the FDA.

Novavax plans to file for Emergency Use Authorization for its NVX-CoV2373 this quarter, and Vaxart will certainly be on investors' radar due to the oral vaccine it's currently developing -- despite the fact that this program has attracted its share of controversy.

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.