What happened

With COVID-19 cases mounting, investors took shelter in vaccine stocks on Monday. By the close of trading, shares of Moderna (MRNA -1.95%), BioNTech (BNTX -0.07%), and Novavax (NVAX -5.87%) were up 17%, 15%, and 12%, respectively.

So what

Moderna's shares received a boost from news that its COVID vaccine was granted provisional registration by Australia's Therapeutic Goods Administration. The drug can now be used to immunize people in that country who are at least 18 years old. Moderna has agreements in place to potentially supply as many as 25 million doses of its vaccine to the Australian government by 2022. 

A person is pointing to an upwardly sloping line on a chart.

Shares of Moderna, BioNTech, and Novavax rose sharply on Monday. Image source: Getty Images.

BioNTech, meanwhile, delivered better-than-expected revenue and earnings in its second-quarter report. The German biotech's sales and adjusted profits checked in at $6.2 billion and $12.67 per share, respectively. That was well above analysts' estimates of $3.8 billion and $8.87 per share. BioNTech now expects to generate a whopping 15.9 billion euros ($18.7 billion) in sales this year. 

At the same time, Novavax appeared to benefit from a Barron's report highlighting institutional buying of its stock. The New York State Common Retirement Fund (the third-largest public pension in the U.S.) boosted its stake in Novavax and other vaccine stocks, according to its recent filings with the Securities and Exchange Commission. 

Now what

If investors grow more fearful that rising coronavirus cases could derail an economic recovery, they're likely to become more defensive in their strategies. That could lead them to pile into the stocks of the major vaccine makers.