A front-runner coronavirus vaccine developed by drug giant Pfizer and German biotechnology firm BioNTech was more than 90% effective at protecting people compared with a placebo saline shot, according to an interim analysis by an independent data monitoring committee that met Sunday.
The early look at the ongoing trial provides a decisive initial glimpse of the real-world performance of one of the four coronavirus vaccines in the last stages of testing in the United States. It is the strongest signal yet that the unprecedented quest to develop a vaccine that could help bring the pandemic to an end might succeed, breaking every scientific speed record.
“I would say it’s a historical moment. Something like this has never happened before. First of all, the world was faced with such a terrible situation, the pandemic, and being able in such a short time to go through what usually takes many years,” Kathrin Jansen, head of vaccine research and development at Pfizer, said in an interview. “Hearing that at the interim analysis we are over 90% effective — it was almost stunning to hear.”
In Pfizer’s 44,000-person trial, there have so far been 94 cases of covid-19, the illness caused by the coronavirus, in people who were not previously infected. Fewer than nine of those cases were among people who received two shots of the vaccine, a strong signal of efficacy. The data is not yet published or peer-reviewed, and the company news release could not be presented to outside experts under the terms of an embargo.
The rapid surge of coronavirus infections in the cooler months, while devastating for the country, means the trial is rushing toward completion faster than company executives anticipated. With more people being exposed to the virus amid the surge, testing the vaccine becomes easier — and faster.
The data committee noted no serious safety concerns. Jansen said the side-effect profile of the vaccine was similar to what was reported in an earlier study. That included pain at the injection site and fatigue, chills and fever — which occurred more frequently in younger trial participants than in adults over age 65.
Pfizer and BioNTech said they plan to submit an application for emergency authorization from the Food and Drug Administration after the third week of November, when they will have two months of safety follow-up data on half of the participants in their trial, along with data on their manufacturing process. The trial will continue until it reaches its endpoint of 164 cases of covid-19, which Jansen said could take a few weeks.
Vaccine development typically takes many years, even decades. But the coronavirus vaccines have been a rare success story in the response to the virus, able to move forward because of a flourishing of new vaccine technologies, a backbone of prior work on emerging pathogens and a mentality that rarely exists in the world of vaccine development — of governments and companies willing to devote nearly unlimited resources to make sure that a vaccine succeeds.
Regulators had set a far lower bar for the minimum performance of a vaccine, requiring it be at least 50% effective. The FDA has also set forth a requirement for five severe cases of the disease in the placebo group, but Jansen said that to preserve the integrity of the trial, Pfizer’s scientists remain blind to the details of the cases at this time.
The vaccine requires two doses, given three weeks apart. Pfizer and BioNTech are working around-the-clock to scale up production, in hopes of having 50 million doses — enough for 25 million people to receive both shots — by the end of the year, and 1.3 billion doses in 2021.
The vaccine uses a new technology never before deployed in an approved medical product. Each injection contains lipid nanoparticles — fat bubbles — that surround a strip of genetic material called messenger RNA. The genetic material carries the blueprint for the distinctive spiky protein that studs the coronavirus surface. After being injected into a person’s arm, the fat capsule delivers its payload to the body’s cells, and the messenger RNA instructs those cells to build the spike protein, effectively teaching the immune system how to recognize and block the coronavirus.
The same approach is being used by Moderna, a biotechnology company that expects to report early results this month for another leading vaccine candidate.
Pfizer, unlike its competitors, did not join Operation Warp Speed, the government initiative designed to erase the financial risk of vaccine and therapeutics development by providing funding to companies and helping coordinate the trials. Instead, Pfizer plowed $2 billion of its own money into the project and then struck a $1.95 billion contract with the U.S. government to provide 100 million doses, contingent on the vaccine being effective.
Its trial initially had a more aggressive design than other late-stage studies in the United States, allowing earlier and more frequent peeks at the data. That raised concern from outside scientists that the company might seek authorization of its vaccine when there were only 32 cases among participants.
The FDA shared those concerns, according to Jansen, and urged the company to wait to do its first data look until there were more cases. Pfizer scientists were initially concerned it would take too long to reach that milestone, particularly as it appeared the pandemic might be coming under control in late summer, thus depriving the study of potentially infected participants. But Pfizer scientists amended their protocol to wait to look at the data until they reached 62 cases as the virus began to surge, and they completed that paperwork last week.
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“We saw that huge upswing, we realized that maybe we should listen and come back to the suggestion of the FDA to have more cases,” Jansen said. “It just shows you the enormous uptick right now of the pandemic, that certainly it took us by surprise — how quickly it really went.”
Once the independent data committee met Sunday, there were 94 cases in the trial — meaning the study is more than halfway done.
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