Why Pfizer Stock Slumped on Friday

Investors were cautiously pessimistic about the latest news coming out of the company’s lab.

In the thick of the coronavirus pandemic several years ago, any positive news from a developer of COVID-19 vaccines or drugs would have been met with a surge of buying in its stock. We’re not in 2021 anymore, though, and an encouraging development from Pfizer (PFE -1.43%) on a combination COVID/influenza jab was met with a collective shrug by the market. In fact, investors traded out of the stock to the point that its price fell by 1.4%, comparing unfavorably to the 0.2% rise of the S&P 500 index on the day.

Combination vaccine falls short in clinical trial

Before market open, Pfizer and BioNTech, the co-developer of its hugely popular Comirnaty COVID shot, published an update on that combination vaccine.

A phase 3 clinical trial involving patients aged 18 to 64 met one of its two primary endpoints, with the combination vaccine successfully achieving immunogenicity against the SARS-CoV-2 virus strain that causes COVID. However, it fell short of doing so for both influenza A and influenza B, producing insufficient immune response for the latter. In their joint press release, the companies quoted Pfizer’s head of vaccine research, Annaliesa Anderson, as saying:

We are committed to developing vaccines that will reduce the burden of respiratory diseases and believe that combination vaccines are the most efficient way to do this. Today’s results provide insight and direction towards achieving this goal, and we remain optimistic about our combination COVID-19 and influenza program, for which we are evaluating the next steps.

Back to the drawing board

The modest sell-off indicated that investors, like the two companies, see enough positives in the late-stage trial not to lose hope in the combination vaccine. COVID is still a threat, and influenza is a constant health scourge. So, if Pfizer and BioNTech can eventually develop an efficacious two-for-one shot, it would almost certainly prove to be a very popular jab.

Eric Volkman has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Pfizer. The Motley Fool recommends BioNTech Se. The Motley Fool has a disclosure policy.

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