What happened

Dynavax (NASDAQ:DVAX) shares were trading 6.5% lower as of 3:35 p.m. EDT on Wednesday after competitor Pfizer (NYSE:PFE) reported data showing its vaccine produces a significantly larger number of antibodies than are found in recovered COVID-19 patients.

So what

Dynavax is collaborating with a number of companies on the development of a COVID-19 vaccine, but trials involving the adjuvant it's contributing to boost immune responses in these collaborations have only just begun, suggesting other players, including Pfizer, may reach the market sooner.

A person speaking through a megaphone.

Image source: Getty Images.

On Wednesday, Pfizer and its partner, BioNTech (NASDAQ:BNTX), announced one vaccine candidate it's evaluating in a small phase 1/2 trial resulted in neutralizing antibody levels that were up to 2.8 times higher than levels seen in recovered COVID-19 patients. The news suggests Pfizer could to deliver on its goal of advancing at least one vaccine into a large, phase 2b/3 clinical trial as early as next month.

Since Pfizer's success suggests it may be further ahead of Dynavax in the race to launching an FDA-approved vaccine, Dynavax's potential market opportunity could wind up being smaller than previously anticipated.

Now what

A number of healthcare companies are in various stages of COVID-19 vaccine development, including Moderna, which is already in phase 2 studies for its mRNA vaccine candidate.

It's too early to say what vaccine will become available first, or which vaccine candidate will work best. A phase 1 trial by one of Dynavax's collaborators, Clover Biopharmaceuticals, recently began enrolling patients, so investors might not want to count the company out yet. If evidence emerges that one of the vaccines incorporating Dynavax's technology produces neutralizing antibodies at a similar or higher level than Pfizer's, it could eventually see its shares rebound.