What happened Shares of BioNTech (NASDAQ: BNTX) were sliding 4% lower as of 12:39 p.m. ET on Wednesday. The decline came after the company and its big partner, Pfizer (NYSE: PFE), 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. 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. 10 stocks we like better than BioNTech SEWhen our award-winning analyst team has a stock tip, it can pay to listen. After all, the newsletter they have run for over a decade, Motley Fool Stock Advisor, has tripled the market.* They just revealed what they believe are the ten best stocks for investors to buy right now... and BioNTech SE wasn't one of them! That's right -- they think these 10 stocks are even better buys. See the 10 stocks *Stock Advisor returns as of November 10, 2021 Keith Speights owns shares of Pfizer. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.Source