What happened

Shares of BioNTech (BNTX -0.27%) were sliding 4% lower as of 12:39 p.m. ET on Wednesday. The decline came after the company and its big partner, Pfizer (PFE -0.12%), announced results from a laboratory study that showed a third booster dose of their COVID-19 vaccine neutralizes the omicron variant at similar levels observed with the original coronavirus strain after two doses. 

So what

Why would the vaccine stock slip on what seems like good news? Probably because the prospects that Pfizer and BioNTech will experience an upsurge in sales of their COVID-19 vaccine due to the omicron variant appear to be lower.

Gloved hands holding a syringe with needle and a vaccine vial.

Image source: Getty Images.

If the current version of the Pfizer-BioNTech COVID-19 vaccine wasn't effective at preventing infection by the omicron variant, the need for a version of the vaccine that specifically targets the variant would've been greater. That would especially be the case if the vaccine wasn't effective at preventing severe disease. The signs now, though, are indicating this scenario is less likely to happen.

It's still early, though. Omicron could prove to be more problematic for the world. Pfizer CEO Albert Bourla mentioned one way that could happen in an interview with CNBC on Tuesday. Bourla noted that the ability of the omicron variant to spread more rapidly could lead to increased mutations in the coronavirus. 

Now what

Pfizer and BioNTech are still developing a variant-specific vaccine for omicron. The partners anticipate having this new version available by March. They also continue to project a manufacturing capacity of 4 billion doses next year.