What happened

Friday wasn't a particularly good day for the stock market overall, but it was even more discouraging for Novavax (NVAX). The coronavirus vaccine developer's stock slipped by slightly over 3% on the day, as good news about a rival shot compounded manufacturing worries about its own.

So what

Earlier in the day, big pharmaceutical company and fellow coronavirus vaccine developer Pfizer (PFE -0.12%) unveiled data showing high efficacy for its Comirnaty vaccine on children. These indicated that Comirnaty, which the company developed in partnership with Germany-based BioNTech (BNTX -0.27%), had a nearly 91% efficacy rate in blocking symptomatic COVID-19 in children aged 5 to 11.

A masked, gloved, and shielded person administers a shot to a masked person in a car.

Image source: Getty Images.

Pfizer and BioNTech have formally submitted the data to the Food and Drug Administration (FDA), which will probably soon authorize the vaccine for use in that age group. So far, Comirnaty is the only coronavirus vaccine fully approved for use by the FDA (shots from Moderna and Johnson & Johnson currently have only Emergency Use Authorization).

This starkly illustrates that, in the U.S. at least, Novavax is significantly behind in the coronavirus vaccine race. The company has yet to file for Emergency Use Authorization for its NVX-CoV2373 vaccine -- it hopes to do so before the end of this year. The company is also holding back from doing so in such jurisdictions as the European Union, the U.K., and Canada. 

Now what

This could very well have much to do with manufacturing challenges. On Tuesday, Politico published an article citing "three people with direct knowledge of the matter," claiming that one of Novavax's top suppliers is having difficulty manufacturing a vaccine that meets regulatory standards.

The company quickly fired off a press release stating that it "confirms our confidence in our ability to deliver our high-quality vaccine" and "underscore[s] our ongoing commitment to the stringent standards of production and manufacturing," to same. The allegations are concerning, however, particularly given that Novavax has much riding on the future of its coronavirus jab.