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November 9, 2020

'Extraordinary': Pfizer's coronavirus vaccine is 90% effective, early data suggests

Daily Briefing

    Pfizer and BioNTech on Monday announced that early data from a trial of their coronavirus vaccine candidate shows the vaccine is more than 90% effective in preventing Covid-19—but experts caution that while the results exceed expectations, it's important to be cautious and wait for the full findings.

    Pfizer's coronavirus vaccine more than 90% effective

    The companies currently are conducting a Phase 3 clinical trial of their mRNA-based vaccine candidate, BNT162b2. The vaccine—which is delivered via two doses, administered three weeks apart—uses genetic material known as messenger RNA (mRNA) that is injected into muscle cells. The vaccine then produces proteins in the body that can trigger an immune response to combat the virus.

    The companies originally planned to evaluate the candidate's efficacy once 32 of the 43,538 people enrolled in the trial contracted Covid-19—that is, tested positive for the virus and presented with at least one symptom—and would continue until at least 164 cases of Covid-19 were reported.

    However, after consulting with FDA, the companies opted to do their first review after 62 cases of Covid-19 had been identified. But by the time they came to that decision, there were 94 cases of Covid-19 in the study. Based on the data at that point in time, a panel of independent experts found that the vaccine was 94% effective in preventing Covid-19 among people who have not previously been infected with the new coronavirus. Specifically, among individuals who were vaccinated, there were 94% fewer cases of symptomatic Covid-19 than among those who received a placebo at seven days after second dose.   

    The independent panel shared its findings with Pfizer and BioNTech, which issued a press release announcing the results. The data has not yet been peer-reviewed or published in a medical journal.

    Pfizer and BioNTech have not publicly released data yet on whether the vaccine is effective at preventing severe cases of Covid-19, nor is there evidence on whether the candidate prevents people from contracting SARS-CoV-2, the virus that causes Covid-19. The companies also do not yet know how long the vaccine provides protection against the new coronavirus.

    The vaccine has been shown to have side effects, including aches and fevers. According to William Gruber, Pfizer's SVP of vaccine clinical research and development, the side effects of the vaccine—including aches and fever—are comparable to other adult vaccines but are likely worse than the pneumonia vaccine developed by Pfizer or a flu shot.

    What's next

    According to STAT News, Pfizer's Phase 3 trial of the candidate is ongoing, and additional findings could affect the reported results.

    That said, Pfizer indicated it may soon request FDA emergency use authorization (EUA) for the vaccine. According to Pfizer, in accordance with FDA guidance, the company will not file for an EUA until at least half of vaccinated trial participants have been monitored for safety issues stemming from the vaccine for a minimum of two months following the second dose. Pfizer said it expects to meet that milestone by the third week of November, at which point they expect to request an EUA.

    Overall, Pfizer said it intends to have enough doses of the vaccine manufactured by the end of the year to immunize 15 to 20 million people, with 1.3 billion available globally in 2021. However, there may be distribution challenges, as the vaccine candidate must be stored at very cold temperatures, making it difficult to deliver the vaccine to certain locations.

    'This is extraordinary'

    Many experts were encouraged by Pfizer's early results, but they emphasized caution until more results are released.

    "I've been in vaccine development for 35 years," William Gruber, senior VP of vaccine clinical research and development at Pfizer, said. "I've seen some really good things. This is extraordinary."

    "If that headline number really holds up, that is huge," Ashish Jha, dean of the School of Public Health at Brown University, said. "This really bodes well for us being able to get a handle on the epidemic and get us out of this situation." However, Jha cautioned that it's difficult to evaluate trial results through a press release and said researchers need to see the full results, noting that side effects are important to watch.

    Similarly, Michael Head, senior research fellow in global health at the University of Southampton in the United Kingdom, said, "We should remain a little cautious. The provision findings are made available in a press release, and the study is ongoing" (Herper, STAT News, 11/9; Thomas et. al., New York Times, 11/9; Hopkins, Wall Street Journal, 11/9; Morello, Politico, 11/9).


    Advisory Board's take

    4 things to watch—and 4 actions to take following Pfizer's vaccine news

    Pam Divack, Senior Analyst and Manasi Kapoor, Senior Director, Life Sciences

    As the Pfizer CEO, Albert Bourla, wrote this morning, "Today is a great day for both science and humanity." Pfizer's promising data provides hope that we may have an effective vaccine in the near future. However, it's important to remember that these data are preliminary. As such, there are four things we will keep watching as the final data are released:  

    • While the early reports of 90% efficacy are exciting, we still need to see the full data set to learn more about safety, side effects, and efficacy in different subpopulations. According to STAT+, the results touting 90% efficacy have not been peer-reviewed by outside scientists or published in a medical journal. We also don't have data (yet) on whether the vaccine can prevent severe cases or even deaths due to Covid-19, or how the vaccine works for different ages, demographics, co-morbidities, etc.—data which may help prioritize vaccine/therapeutic allocation and distribution. One positive is that the study recruited a diverse set of volunteers—about 42% of global participants and 30% of U.S. participants have racially and ethnically diverse backgrounds, according to STAT+—which will likely help build trust and confidence in the efficacy among different groups.
    • If this vaccine does receive an emergency use authorization, Pfizer and/or the government will need to launch a serious public health campaign to encourage people to take the vaccine and overcome public skepticism. The general public is already highly skeptical of a vaccine—according to a PEW survey conducted in September, 49% of people say they definitely or probably would not get vaccinated at this time. Given that early data have indicated the vaccine causes some side effects, such as aches and fevers, public health authorities are going to need to educate people about the vaccine, the nature of the side effects, and the importance of widespread vaccination as a lever to improve public health.
    • Pfizer's plans to use their own system to distribute the potential vaccine, rather than use the government's chosen distribution partner (McKesson), may enable a quick and efficient rollout. However, Pfizer will need to communicate their distribution plans to health systems, vaccination sites, and the general public in a timely and transparent manner. According to STAT+, "Pfizer says up to 50 million doses could be available globally by the end of the year, with 1.3 billion available in 2021." While shipping and storage at cold temperatures will be a key challenge, Pfizer's plans to operate distribution on their own gives them more control, expertise, and potential speed in rollout.
    • Although Pfizer will continue to monitor trial participants even after the company files for an emergency use authorization, they will need to create a robust plan to collect post-approval, real-world data about the vaccine’s long-term safety and efficacy. Pfizer will need to track both trial participants and real-world patients over a longitudinal period of time to identify any potential long-term side effects, to understand treatment durability, and to collect additional data about long-term efficacy. Doing so will enable Pfizer to continue to build public trust and confidence in the vaccine.

    This exciting news underscores the need for health care leaders to start preparing for a future vaccine today. As we await more data, health care leaders can take a few action steps today:

    • Start communicating with patients about the potential for a vaccine in the near future, highlighting the risk/benefits of taking a vaccine and the potential to improve public health.
    • Anticipate and prepare to combat misinformation about the vaccine and answer questions about the data and the vaccine approval process overall.
    • Prepare your supply chains accordingly, where possible, and begin ensuring adequate capacity to distribute, store, and administer a vaccine locally.
    • Determine staff/supply needs to manage the vaccine distribution process and manage/track patients.

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