It took a global pandemic to accomplish one of the most significant advances in the history of vaccinology: widespread, commercial deployment of vaccines derived from nucleic acids. As of this writing, hundreds of millions of people have been vaccinated against SARS-CoV-2, the virus that causes COVID-19. And most of those shots have been the Pfizer–BioNTech and Moderna offerings, which are both of a type known as an mRNA (messenger RNA) vaccine.
Conceived decades ago but released to the public for the first time during the pandemic, mRNA vaccines so far are living up to their promise. Both the Pfizer and Moderna vaccines have proven to be about 95 percent effective against the novel coronavirus. In addition, this kind of vaccine can be tweaked with relative ease to target new variants of a virus, and its production does not rely on items that can be difficult to produce quickly in enormous quantities. And yet, a couple of drawbacks of mRNA vaccines have also been widely noted over the past six months: They depend on deep-freeze supply chains and storage, and they can produce significant side effects such as fever, chills, and muscle aches.
So hopes remain high for another kind of nucleic-acid vaccine, one that makes use of DNA rather than mRNA. DNA-based vaccines have most of the advantages of mRNA vaccines, yet they produce no significant side effects—and, crucially, they don’t need to be refrigerated. These attributes could make these vaccines a boon to rural and low-resource regions. “If we really have to vaccinate 7 billion people, we might just need every possible technology,” says Margaret Liu, chairman of the board of the International Society for Vaccines.
Inovio’s device uses a technique called electroporation to sneak a DNA vaccine into cells. Kate Broderick, Inovio’s senior vice president of R&D, has been working on this technique for years, but the pandemic provided both motivation and funding to accelerate development. Spencer Lowell
DNA vaccines come with a major challenge, however. When administered with an ordinary hypodermic needle, they’ve conferred only weak immunity, at best, in many human studies. But if a small, ambitious Pennsylvania company backed by the U.S. Department of Defense succeeds in its clinical trials, DNA vaccines—enabled by a new delivery technology—could soon join the fight against COVID-19, and a host of other viral illnesses.