What happened

Shares of several COVID-19 vaccine companies were jumping as of 11:43 a.m. ET on Monday. BioNTech (BNTX 1.38%) was the biggest mover, with its shares soaring 14.7%. Dynavax Technologies (DVAX 0.34%) was vaulting 5.9% higher. Novavax (NVAX 2.52%) stock was up 5.2%. Even shares of pharmaceutical giant Pfizer (PFE 1.00%) were rising 4.3%.

Of the four companies, only Pfizer announced any news today. The company stated that it will continue to supply medicines to Russia. However, Pfizer plans to donate all profits made by its Russian subsidiary to "causes that provide direct humanitarian support to the people of Ukraine."

This update on Pfizer's position in Russia wasn't the reason for its stock gains. Instead, all four vaccine stocks rallied as part of an overall bounce for the stock market. Lower oil prices appear to be fueling the broader market move. 

In addition, China is experiencing its worst COVID-19 outbreak since early 2020. Investors who might have begun to think the pandemic was nearing an end could be rethinking their positions based on this news. 

So what

We're seeing the old adage that "a rising tide lifts all boats" in action today. Most stocks move higher when the overall stock market delivers big gains. And most COVID-19 vaccine stocks are jumping with the news from China. But why is BioNTech enjoying a greater bounce than Dynavax, Novavax, and Pfizer? 

One possible explanation is that the hardest-hit stocks in a major market decline are often the ones that rebound the strongest. Before today's moves, both BioNTech and Novavax stocks had plunged more than 45% year to date. Dynavax stock was down around 30%, while Pfizer's share price had slid roughly 15% lower.

However, there's also another factor at play. BioNTech and its partner Fosun Pharmaceutical hope to soon win approval in China for BioNTech's COVID-19 vaccine. The recent surge in COVID-19 cases in the country could translate to a greater opportunity for the two companies if the vaccine is approved in China.

A person wearing a face mask with people walking on a city street in the background.

Image source: Getty Images.

Now what

Look for the overall stock market performance and the COVID-19 situation in China to remain key forces behind how all four of these vaccine stocks fare in the coming weeks. In some respects, the Chinese story is the more important thing for investors to watch. If the resurgence of COVID-19 in China is the beginning of another wave that spreads across the world, the demand for COVID-19 vaccines could increase.  

It's too soon to predict such a scenario will unfold. However, we're seeing that any expectations that COVID-19 vaccine demand would fall significantly going forward are also premature.