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Pfizer and BioNTech announced this week that their vaccine was 90 percent effective in preventing symptomatic COVID-19 in clinical trials. The data is still preliminary and has not been examined by independent researchers, but it is good news for both this specific vaccine and the other coronavirus vaccines in the works, especially those that are based on the same genetic technology.
“It’s extremely encouraging, in my opinion, not just for the Pfizer vaccine, but generally for the platform,” says Ross Kedl, an immunologist at the University of Colorado.
The Pfizer and BioNTech vaccine is made from genetic material called mRNA. The mRNA carries instructions inside cells and tells them to build proteins. The vaccine includes a specific piece of mRNA that contains instructions on how to make the coronavirus spike protein, which is the small portion that allows it to bind to human cells. The vaccine stimulates the human body to make copies of this protein. When the immune system finds those spikes, it learns to recognize and block them.
Gene-based vaccines are relatively simple to develop and manufacture. For years, they have been heralded as the future of vaccine development. However, until now, they have been largely experimental. The Food and Drug Administration (FDA) has never approved one for use in humans. Rosemary Rochford, also an immunologist at the University of Colorado, says she was initially skeptical that they would work as well as some other types of vaccines, such as those made with inactivated viruses. But the Pfizer data, assuming it stands up to further evaluation by outside experts and the FDA, is a solid proof of concept. “This mRNA platform appears to be very promising,” he says.
The Modern vaccine candidate, which should publish initial data soon, is also based on mRNA. “I would assume that their efficacy will probably be similar,” says Drew Weissman, an immunologist at the University of Pennsylvania who conducted the research behind the mRNA vaccines. He is also an advisor to BioNTech, the company that partnered with Pfizer on this vaccine.
Moderna and Pfizer / BioNTech also achieved equivalent results in their phase 1 and phase 2 clinical trials, which are smaller in scale, Kedl says. “You could almost overlap the two, or change the names and you would fool everyone. They both really strongly support each other in terms of the strength of immunity. ”
Before the COVID-19 pandemic, not much research had been done on gene-based vaccines for infectious diseases; Much of the work focused on treating cancers, not viruses, says Rochford. The approval of the first gene-based vaccine for something like COVID-19 would open up a whole new world of options for vaccine developers.
Pfizer’s vaccine has not yet been cleared or approved by the FDA, and there are still a few steps left before it gets to that point. However, data released this week points in that direction.
“I think it’s a game changer,” says Kedl. “I wouldn’t be surprised if, in the next 10 years, we see this make its way into the flu vaccine.”
Once these vaccines get past the initial hurdle of proving effective and safe, researchers can begin to study them more intensively. “Once we know it works, we’ll take some time to find out why,” says Kedl.
Rochford says she will be watching to see how long the immunity provided by these mRNA vaccines is maintained and how long the antibody response that the vaccine generates lasts. Research shows that for people who contract COVID-19 and produce their own natural antibodies, levels drop before stabilizing. But the antibodies generated by vaccines are different. “Your body is not fighting an infection and a whole disease process,” he says. “I am more confident that the durability will be better than what we see in a natural infection.”
Companies and researchers will also be looking for ways to improve vaccines. According to early reports, they cause more pain and other minor side effects than other vaccines, for example. “There may be some modifications, we can start to change some things,” says Kedl.
A disadvantage of mRNA vaccines is that they must be stored at an extremely low temperature, which makes them more difficult to transport. MRNA is an unstable compound, and keeping it cold ensures that it does not break down before injecting it into a patient’s arm. Weissman says teams at pharmaceutical companies are working on ways to keep these vaccines stable at higher temperatures, and he believes future generations of COVID-19 vaccines will be able to stay in refrigerators. Weissman is also working on a way to freeze-dry the genetic material, so that the vaccines can be stored at room temperature. “I don’t think that’s going to be a big concern,” he says.
Having another proven way to make vaccines will help researchers prepare for the next pandemic. There is nothing unique about this specific coronavirus that makes mRNA vaccines work well; the platform could be just as effective for other viruses. “Let’s say we have a new coronavirus, or a new Ebola virus, or a new emerging pathogen,” says Rochford. “It would be pretty easy to generate them once you have the sequence and some basic biology. Going forward, it gives us a very strong platform for a quick response. “
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