“We need vaccines,” immunologist Jacob Glanville says. He knows about combating infections; the fast-talking, curly-haired former Pfizer staff scientist has spent years searching for a universal flu vaccine, and his San Francisco-based startup Distributed Bio spearheads a variety of vaccination projects. As one might expect, his team is working diligently to find biopharmaceutical tools to fight Covid-19, but here’s the twist: It’s opting out of the scientific community’s sprint to find a vaccine. Instead, Distributed Bio is part of a parallel coronavirus research scramble: the hunt for antibody treatments.

Along with a wide mix of research teams in laboratories across the world, Glanville is pursuing antibody treatments as a complementary tool to fight Covid-19. Unlike vaccines, antibody treatments don’t produce lasting protection against a disease. Instead, these treatments are meant to equip bodies with tools to immediately (albeit temporarily) fight off an infection, or prevent an imminent contagion.

This is partly a matter of timing. “Vaccines take forever,” Glanville says. Traditional trials require administering the vaccine to healthy people, then observing whether they develop immunity. Proving efficacy necessitates waiting. And waiting. Even though buzzy biotech companies like Moderna have managed to leap into human trials in a matter of months, many researchers still doubt the optimistic immunization timelines put forth by politicians and pundits. “I think antibodies have a faster pathway to deployment,” says Robert Carnahan, the associate director of the Vanderbilt Vaccine Center, which is also working on its own antibody treatment research. “We either let everybody get the disease or we get a vaccine, and antibodies can bridge us to that moment where we have it.”

When exposed to viruses, immune systems create antibodies, proteins that protect the body from foreign substances. This is happening to people who are fighting SARS-CoV-2 around the world. The antibodies linger in their blood after symptoms subside, protecting from further infection. Right now, the blood plasma from recovered coronavirus patients can be transfused into people who are currently fighting the disease, as a way to introduce effective antibodies into their systems. Using blood from recovered patients to fend off disease is an old treatment, and convalescent serum has been used to treat MERS, SARS, and Ebola patients. So far, it appears convalescent serum can help people who are infected with Covid-19 recover. However, it has several major drawbacks. The most obvious is a matter of scale. There’s a finite supply of convalescent blood in the world, so it simply isn’t possible to harvest enough of it, even if every single previously infected person happily gave blood every week. Collecting and distributing the blood is also a complicated, labor-intensive process.

And there’s another problem, which is that the process just isn’t that efficient. Each donor’s blood would contain antibodies to a wide swath of previous infections, not just Covid-19. So the number of antibodies in their serum that can actually fight this particular virus might be very low. Antibody treatments apply the logic of convalescent serum and refine its concept by creating more targeted, potent, and scalable versions of the kinds of antibodies we produce that can banish Covid-19, produced en masse in labs rather than drained from human arms. Ideally, the treatment process itself would also be much less cumbersome than the serum infusion. “You might be able to do a subcutaneous injection, like an outpatient procedure,” Glanville says.

Read all of our coronavirus coverage here.

Of course, the therapeutic dose is currently only a hypothetical. Scientists are still in the arms race portion of their research, and it’s not clear which type of antibody treatment will pull ahead. Many already believe they have pinpointed effective antibodies, and have evidence that they can neutralize Covid-19. But they still need to make sure the antibodies that look promising in a laboratory setting will work when introduced to infected animals, and then that they will work when introduced to infected humans—and then that they are able to be mass-produced in a safe, cost-effective, and timely manner. “There are a lot of different approaches that people are trying, all of which hold promise,” says Yale University chemistry professor David Spiegel, who also co-founded a New Haven-based pharmaceutical company called Kleo Pharmaceuticals. “It’s experimental science.”