- Pfizer’s experimental coronavirus vaccine succeeded in the final stage of clinical trials, the drugmaker said Monday, a milestone in society’s fight against the pandemic.
- Developing an effective vaccine against a brand-new virus in less than a year is an unprecedented feat in medicine.
- The study found people who got Pfizer’s shot were less likely to develop COVID-19, the disease caused by the novel coronavirus. The drugmaker said the shot was found to be more than 90% effective in preventing COVID-19.
- Pfizer described the results in a press release. The trial is still ongoing, and the interim results have not been published in a peer-reviewed medical journal.
- The vaccine will not be distributed immediately. It still needs to be evaluated by the US Food and Drug Administration.
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A leading coronavirus vaccine candidate worked to prevent people from developing COVID-19, a milestone in society’s war against the pandemic.
The pharmaceutical company Pfizer on Monday said its vaccine succeeded in the final stage of clinical trials, which compared tens of thousands of volunteers who received two doses of the experimental vaccine against a group receiving a saltwater placebo.
The drugmaker said the shot was found to be more than 90% effective in preventing COVID-19, based on 94 cases of the disease observed in the study.
Next, the New York drugmaking giant plans to apply for emergency authorization that would allow it to distribute the shot more widely. The company still needs more data on how safe the vaccine is before asking for the emergency OK, and it has said it won’t have the necessary information until later this month.
Pfizer and its German partner BioNTech are the first to report positive results from a pivotal trial of a COVID-19 vaccine. Developing and testing an effective vaccine in less than a year is an unprecedented accomplishment in medicine. Shares of Pfizer and BioNTech soared in premarket trading Monday morning. Markets broadly rose on Monday, celebrating the success of the vaccine as a critical piece to confronting the pandemic.
While the study is still ongoing and will collect follow-up safety and efficacy data, the key conclusion from an interim analysis is that the vaccine works.
“Today is a great day for science and humanity,” Pfizer CEO Albert Bourla said in a statement. “The first set of results from our Phase 3 COVID-19 vaccine trial provides the initial evidence of our vaccine’s ability to prevent COVID-19.”
Questions remain, however, such as how long the vaccine will work for and whether any rare, yet serious, side effects have yet to be detected.
The impact of the success won’t be immediate on society. Key challenges now shift from the scientific realm to regulatory, logistical, and political. Regulators have to review the data and decide whether there’s enough evidence to approve the shots. Supplies will also be extremely limited for the first few months as production is ramped up.
Pfizer’s vaccine will also pose unusual logistical challenges. It needs to be shipped and stored at minus 94 degrees Fahrenheit. The Centers for Control Disease and Prevention has estimated the US will have a supply of about 20 million to 30 million doses of Pfizer’s vaccine in 2020, translating to enough doses to vaccinate less than 10% of the US population.
If the vaccine gets an emergency approval, it won’t be available to everyone at once. The first people eligible to get the shots may be those at high-risk of falling ill, such as frontline healthcare workers and older people.
While the study succeeded in its primary goal of reducing symptomatic COVID-19 cases, that may not necessarily mean the shot prevents asymptomatic infection or serious illness.
That means vaccinated people could still be unknowing carriers of the virus and may still face a risk of developing severe COVID-19 that requires hospitalization and may even result in death. Longer-term data from the study could help answer these questions.
Initial results are limited, but Pfizer touts strong efficacy
These results came from an interim analysis of the study, which is still ongoing. The trial will carry on through its final analysis of 164 COVID-19 cases, which should help produce more rigorous results over time.
The trial recruited 43,538 volunteers, randomly given the vaccine or placebo injections. Researchers designed the study to count COVID-19 cases among the trial participants. Once a certain number of volunteers got sick, an independent board of experts reviewed the data to see whether those getting the experimental vaccine were far less likely to fall ill than those getting the saltwater placebo.
The primary goal was to see whether the vaccine reduced COVID-19 cases after getting both doses. The trial protocol specified a COVID-19 case as someone who both tests positive and displays symptoms. Researchers counted cases starting a week after the volunteer received the second dose. Pfizer on Monday said protection from the virus was achieved after 28 days after the initial dose.
There is no long-term follow-up data available for people given Pfizer’s vaccine. That means critical questions about the durability of the shot’s protection as well as the risk of any long-term side effects remain unknown.
The study will carry on to address those questions. Experts noted that vaccine trials are rarely able to identify ultrarare side effects, which can be one-in-a-million events. US health agencies have surveillance systems to track vaccine efficacy and safety after a shot is released to the public.
Pfizer is preparing for a speedy approval
Through the coronavirus vaccine initiative Operation Warp Speed, the US government has spent months preparing for success in the clinic.
The US government reached a deal in July with Pfizer to buy 100 million doses for $1.95 billion. That contract also included an option to buy up to 500 million more doses. Pfizer has reached deals with dozens of governments around the world, beyond the US, allocating fragments of initial supply to many countries.
In total, Pfizer expects to make 50 million doses in 2020 and up to 1.3 billion doses in 2021.
The US Food and Drug Administration will decide whether to authorize the experimental vaccine. The agency is expected to quickly convene an independent panel of experts to review the data after Pfizer submits its application. While Pfizer has said it should have enough safety data from the study by the third week of November to submit the vaccine for review, it’s unclear how quickly the regulatory process will move from there.
The FDA’s expert panel typically has a lengthy public meeting to ask questions about the rigor of the data and the risks and benefits of approving an experimental medicine. FDA scientists then take that group’s recommendations into consideration and ultimately make an approval decision.
Typically, the agency takes six to 10 months to review applications for new drugs and vaccines. While it’s widely expected that timeline will be dramatically accelerated given the urgency of the pandemic, a precise timetable is unclear.
More results expected in coming months for rival COVID-19 vaccines
While Pfizer’s vaccine is the first to report successful late-stage trial results, several other drug developers are aiming to quickly follow with results for their own vaccines.
The other frontrunners are the Massachusetts biotech Moderna; the British pharma giant AstraZeneca and the University of Oxford; the world’s largest healthcare company, Johnson & Johnson; and the small Maryland biotech Novavax.
Vaccines developed by all those drugmakers have started the final stage of clinical testing. Moderna expects to report results in November, while AstraZeneca is aiming to have data before year’s end. J&J and Novavax will most likely have results slightly later, aiming for late 2020 or early 2021.
Pfizer’s success is expected to boost confidence in other vaccines, as all these shots target the same portion of the coronavirus: its spike protein. It is also validation for promising technology in vaccine research that has remained unproven until now. Pfizer’s candidate is a messenger RNA vaccine, which requires just the genetic code of the virus to engineer an experimental vaccine.
Pfizer’s readout is the first success in an efficacy-focused study to show the technology works in humans. Moderna also specializes in mRNA therapeutics and vaccines and was the world’s first drugmaker to start testing a COVID-19 vaccine in humans in March.