On Tuesday, Pfizer (NYSE:PFE) and BioNTech (NASDAQ:BNTX) agreed to collaborate on the development of an experimental vaccine to prevent COVID-19 transmission. BioNTech's U.S. partner signed a letter of intent shortly after Fosun Pharma agreed to assist development efforts in China.

Pfizer didn't have any financial details to share, but the U.S. pharma giant appears committed to helping BioNTech's experimental vaccine as quickly as possible.

A COVID-19 blood sample

Image source: Getty Images.

Second in class

BioNTech's one of several companies that wants to deliver strands of messenger RNA (mRNA) into cells where they're supposed to direct the production of useful proteins. If it works as expected, the company's COVID-19 vaccine candidate BNT162 should allow patients to produce an identical copy of a protein found on the surface of the coronavirus responsible for COVID-19.

BioNTech expects to begin injecting people with BNT162 by the end of April, which is ambitious but not as fast as Moderna (NASDAQ:MRNA). Working in partnership with the National Institutes of Health, Moderna recently began dosing patients with an experimental coronavirus vaccine that works along the same lines.

Cool your jets

Unfortunately for impatient biotech investors, regulators usually want to see a preventative benefit that lasts at least a year. Without a time machine, it just isn't possible to prove safety and efficacy on a shorter timeline. 

Timing isn't the only problem. Vaccine math is hard, and the vast majority of experimental vaccines developed with proven methods eventually fail to provide evidence of a statistically significant benefit. 

Dismal odds of success haven't stopped the market from making BioNTech a $16.9 billion company at recent prices. That's an enormous sum for a company that has no products to sell yet. If investors catch a whiff of trouble with BNT162, the stock could implode overnight.