On Wednesday, the pharmaceutical company Pfizer announced even more encouraging results from its now-completed covid-19 vaccine trial. The experimental vaccine appears to be 95% effective at preventing illness overall and seems nearly as effective in people over the age of 65, a key population. Despite the very promising findings, though, there’s still a long road ahead before most people can expect easy access to a vaccine and the pandemic reaches its end.
This vaccine is a joint collaboration between the German pharmaceutical BioNTech and Pfizer, with BioNTech largely responsible for its development in the lab, while Pfizer has bankrolled the clinical research. It’s based on a novel vaccine technology that uses messenger RNA (mRNA) to tell the body’s cells to create inert bits of spike protein from the coronavirus (the spike protein helps the virus infect cells). These bits are supposed to provoke a reaction from the immune system that trains it to recognize and defeat the real germ, should it ever come around.
Their Phase III clinical trial recruited over 40,000 volunteers and randomized them to either take two doses of the vaccine (21 days apart) or a placebo. Researchers decided prior to the study’s start that it would reach its primary endpoint once 170 people developed covid-19 across both groups. This may not sound like a lot, but it’s a number that should allow researchers to make a fair comparison between the two groups. That goal has now been met.
The results were announced by Pfizer Wednesday morning in a press release. Out of 170 people with covid-19, 162 people were in the placebo group and eight had received the vaccine, suggesting the vaccine is around 95% effective. Unlike the results presented almost two weeks ago by Pfizer—based on 94 volunteers—the company has now provided more specific patient data as well.
The rate of effectiveness was similar across gender, race and ethnicity, and age; in people over 65, the vaccine appears to be 94% effective. Of the eight vaccinated volunteers who developed covid-19, only one developed severe illness, while nine severe cases were found in the control group. No serious safety concerns were detected among vaccine-takers, with the most common severe adverse effects limited to fatigue (reported by 3.8% of volunteers in data collected so far) and headache (2%) after the second dose.
With the primary goals of the study now met, the company plans to file for an emergency use approval from the Food and Drug Administration in a matter of days.
“The study results mark an important step in this historic eight-month journey to bring forward a vaccine capable of helping to end this devastating pandemic. We continue to move at the speed of science to compile all the data collected thus far and share with regulators around the world,” said Albert Bourla, chairman and CEO Pfizer, in a statement released by the company.
The results are nearly identical to those presented just this Monday by the Massachusetts-based pharmaceutical Moderna. Both vaccines rely on mRNA, and both companies have entered into contracts with the U.S. government to mass-produce up to 100 million doses should the vaccine prove effective. Moderna has signaled that it too will file for an emergency use approval from the FDA very soon.
To be clear, the findings from both companies are as good news as one could have hoped for at this point. It wasn’t too long ago that experts would have been satisfied with a vaccine only 50% effective—that alone would have been enough to seriously turn the tide against the pandemic. This level of effectiveness, should it be genuine, would be one of the highest ever seen for a vaccine, and it bodes well for the other covid-19 vaccines in development, most of which are focusing on the same spike protein targets of the virus.
But the caveats are also important to keep in mind. Right now, all of this is based on preliminary data that hasn’t been made publicly available (the data is said to have been analyzed by a panel of independent scientists, however). Even if this is all on the level, we’re still making assumptions about how the vaccine will work in real life based on a small number of cases, which is why it’s necessary to keep an eye on the participants in these trials moving forward, as well as on people who receive the approved vaccine once it is available.
Another glaring question that can’t be answered right now is how long vaccine-provided immunity will last, as well as its potency. It’s possible, for instance, that a vaccine could prevent most people from becoming sick, but not entirely prevent their ability to transmit a silent infection to others. To understand this risk better, scientists will need information on how much virus, if any, can be found in vaccinated people recently exposed to infection—something that the clinical trial data may hopefully provide once it’s been unpacked in full. The volunteers in the Pfizer trial and others will be tracked for the next two years to test for long-term immunity and any other possible safety risks of the vaccine.
Beyond the scientific questions are the logistics. Pfizer’s vaccine requires extreme cold temperatures to be kept viable, a resource that isn’t available right now everywhere in the U.S., particularly in rural areas with few medical centers. However, Moderna’s vaccine is said to require only standard refrigeration. In either case, though, it will take time to build up the stockpiles of vaccines needed to reach everyone in the country.
It’s expected that the FDA will make a decision on whether to approve either or both vaccines for emergency use sometime in December, with doses being given out later that month or in early January. But even so, only a limited supply will be available then, and it’s likely these vaccines will be prioritized for front-line health care workers. Both the incoming Biden administration and health experts have cautioned that it may take months before the general public can have easy access to any successful vaccine. Even once available, there will still be the challenge of ensuring that people feel comfortable enough to take a vaccine—something that’s become harder in recent years.
None of this pessimism is meant to take away from the tremendous accomplishment on display here. To have created not one but two vaccines with seemingly high effectiveness in less than a year is unprecedented, and it’s a credit to the hundreds, if not thousands of scientists who have worked tirelessly during the pandemic. And there are still more vaccines now racing to the finish line, which could fill other unmet needs, such as being inexpensive enough to mass produce for lower-income countries.
Personally, I’m cautiously optimistic about the course of the pandemic in the medium- to long-term, given these vaccine results. However, I’m deeply concerned about the short term. The pandemic has reached a terrifying new peak, both in the U.S. and worldwide. Last week, according to data collected from the World Health Organization, was the deadliest recorded so far, with almost 60,000 deaths worldwide. This week doesn’t seem to be shaping much better. It’s likely that deaths in the U.S. will surpass over 2,000 a day by Christmas, and there’s no sign of the pandemic abating anytime soon, nor of the federal government doing much of anything about it.
Hope is absolutely on the horizon, but it’s going to be a very rocky last mile getting there.