Shot of Optimism

The Pfizer vaccine results spell good news for 2 unexpected reasons

"I think it's the first time we can say there's a light at the end of the tunnel."

Originally Published: 
Iryna Veklich/Getty Images

Pfizer — one of the many companies working towards a coronavirus vaccine — announced Monday its early coronavirus vaccine results. Per a press release, it appears to be 90 percent effective in preventing infection.

The news suggests a potential pivot toward the positive in the fight against coronavirus.

Kathrin Jansen, a senior vice president and the head of vaccine research and development at Pfizer, called the release of this data "a historic moment."

Editor's Note, 11/18/20: Pfizer announced the completion of its Phase 3 clinical trial on Wednesday. Out of 170 confirmed cases of Covid-19, eight were in the vaccine group. That puts the efficacy of the vaccine around 95 percent, per a company press release. That puts the data in league with Moderna's vaccine, which demonstrated 94.5 percent efficacy according to interim data released November 15.

Full data have not yet been released, but the announcement breaks down how the vaccine fared in elderly populations and in those with severe disease – two populations critical for controlling the pandemic's worst effects.

The release says that the vaccine was over 94 percent effective in people 65 and older, although no specific data has been provided. Of the 10 severe cases documented in the study, nine were in the placebo group and one in the vaccine group — suggesting the vaccine works well to prevent severe disease.

The trial also notes that the vaccine passed the FDA's safety data milestone and was "well-tolerated." The most drastic side effects reported in the release were fatigue and headache.

Next, Pfizer plans to pursue an emergency use authorization for the vaccine and will submit paperwork "within days."

Scientists have called on Pfizer to release the full data (the company indicated it would share data with regulatory agencies in the press release). However, the data is still better than scientists were expecting. As Akiko Iwasaki, an immunologist at Yale University told The New York Times: "It’s pretty amazing."

Stephen Goldstein, an evolutionary virologist who studies coronaviruses at Utah University Health, was not involved with the study. He says that this news represents a turning point, but not just because it suggests that this single vaccine candidate is on the right track.

Two especially encouraging takeaways? The results could mean other vaccine candidates that either use similar delivery methods or also target the spike protein may also perform well.

That 90 percent effectiveness number is based on the partial results of Pfizer's Phase 3 clinical trial – the third and largest stage of human testing in the vaccine development process. The vaccine, manufactured in a partnership with German company BioNTech, is being tested in a sample of 43, 538 people.

But the data backing up the 90 percent effectiveness result is based on a sample of 94 people. The vaccine prevented infection in 90 percent of people in that small group who had not been previously exposed to coronavirus, the company's press release notes. A full paper has not yet been released and the final data will be released when 164 cases of Covid-19 have occurred in the study sample.

That 90 percent number, should it hold up, would place Pfizer's coronavirus vaccine in league with some of the most famous, and effective, childhood vaccines like the measles vaccine (two doses of which is 97 percent effective in preventing disease), or the smallpox vaccine.

Early data from a Pfizer's Covid-19 phase III vaccine trial were promising.


What this means for other vaccines – The Pfizer vaccine candidate is an mRNA vaccine. That means it uses tiny bits of messenger RNA to trick the body into producing some recognizable features of a virus. In this case, that feature is the spike protein, which the coronavirus uses to latch on to cells.

The FDA has never approved an mRNA vaccine. But other mRNA vaccines are in the works. Moderna Inc., another company in Phase 3 coronavirus clinical trials, also uses this technique to train the immune system.

"They should be they should be next to report data, I would think," Goldstein says. "It's encouraging that they should get similar results."

It does come with some caveats: mRNA vaccines, for example, need to be kept extremely cold. Pfizer has already started making coolers for this purpose.

"... it's at least proof-of-concept that just having spike is sufficient to produce protective immunity."

The Pfizer vaccine also aims to manufacture just the spike protein using that mRNA blueprint. It doesn't produce other factors to train the immune system, Goldstein explains. That's potentially a promising signal to other vaccines that use different technology but manufacture the spike protein too.

"If a spike-only vaccine produces effective immunity, although the delivery platform for those is different, it's at least proof-of-concept that just having spike is sufficient to produce protective immunity," Goldstein says.

For example, the vaccine manufactured by AstraZeneca in partnership with the University of Oxford uses a chimpanzee adenovirus to manufacture the spike protein. The same goes for Johnson and Johnson's vaccine candidate, though that vaccine manufactures the spike protein using a mild, human adenovirus. Both of these candidates are also in Phase 3 clinical trials.

The spike protein alone may still get the job done, suggesting these methods are in play too.

The Pfizer vaccine trains the body to manufacture the spike protein, which then teaches the immune system to recognize the coronavirus.


Where do we stand right now? –  The Food and Drug Administration will approve a vaccine that is more than 50 percent effective in preventing or lessening disease. Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, guessed that we might see a vaccine that's about 75 percent effective.

This result suggests the coronavirus vaccine may be better than anticipated. However, Pfizer/BioNTech vaccine's effectiveness isn't set in stone.

We still don't know the ages of the people released in this sample of 94 people, Susanne Hodgson, a lecturer and clinical research fellow at the University of Oxford's Nuffield Department of Medicine tells Inverse. That means it's still not clear how it affects immunity in elderly people who are at high-risk for severe Covid-19.

Beyond that, even a vaccine released into the real world may show different levels of effectiveness than the one advertised in early studies.

"Vaccine effectiveness [real-life efficacy] often differs from efficacy outputs from vaccine studies," Hodgson says. "But overall, of course, this is a very encouraging result."

Goldstein adds that this result should encourage us to prevent as many infections this winter as possible. If there really is a light at the end of the tunnel, adhering to social distancing and wearing masks could ensure that more people make it there.

"It's really a case for people to be buckling down now," he says.

"I think it's the first time we can say there's a light at the end of the tunnel."

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