What happened

Shares of BioNTech (BNTX -3.23%) were jumping 8.4% as of 11:45 a.m. EST on Monday. The company didn't report any new developments today or over the weekend, though, that could have served as a catalyst. Instead, some investors appear to believe that BioNTech's sell-off last week went too far.

So what

The vaccine stock certainly hit a rough patch in recent days. BioNTech's shares fell 22% last week. Most of the decline came after Pfizer (PFE -3.07%) announced great results from a clinical study of its experimental COVID-19 pill.

A healthcare professional giving a shot to a person.

Image source: Getty Images.

Investors were concerned that the potential availability of safe and effective COVID pills could hurt sales of COVID vaccines, including Pfizer's and BioNTech's Comirnaty. Prior to Pfizer's good news on Friday, Merck (MRK -0.01%) and its partner Ridgeback Biotherapeutics announced positive results for their COVID pill, molnupiravir.

However, it's important to remember that (at least for now) governments are buying COVID vaccines. They're not likely to reduce their focus on vaccinations even with oral COVID therapies on the market. Pfizer's pill will probably have minimal impact on supply deals for Comirnaty in 2022 and 2023.

Now what

Over the longer term, COVID vaccine sales could be lower if the COVID pills are authorized for post-exposure prophylaxis. That could especially be the case if the U.S. government steps back from buying COVID vaccines. But there's a lot of uncertainty about how the dynamics of the COVID vaccine market will shake out beyond 2023 anyway.