UPMC and University of Pittsburgh medical researchers announced a “scientific breakthrough” in a Tuesday afternoon news conference that may provide the key to fighting COVID-19.

But the breakthrough isn't a vaccine. It's an antibody. And it is expected to both prevent and treat COVID-19 infections.

“A vaccine induces antibodies,” said Dr. John Mellors, chief of infectious diseases at UPMC. “A vaccine cannot treat an established infection.”

Dimiter Dimitrov, director of the University of Pittsburgh's Center for Antibody Therapeutics, started working with assistant director Wei Li and other scientists this spring to identify an antibody that neutralizes the SARS-CoV-2 virus.

The antibody has been used to develop a drug called Ab8.

“We found that it's not just important for treatment,” Dimitrov said. “But also for prevention.”

Mellors said Ab8 is a highly effective treatment for several reasons.

For one, it's able to fight the spike proteins SARS-CoV-2 uses to latch onto and bind with healthy cells.

“Think of it as a key and a lock,” Mellors said. “It prevents the key from getting into the lock.”

The Ab8 antibody is also tiny — measuring 10 times smaller than a full-sized antibody — and potent.

“The small size means we can treat ... more people,” Mellors said. “Because we need less of it.”

Ab8 doesn't necessarily need to be injected into the bloodstream either. It can be taken via inhalation and other alternative methods, according to Mellors.

Ab8's main purpose will be to block infection, Mellors said. It also acts as an alternative for people who are historically unable to receive vaccinations, such as those with egg allergies.

Mellors said Ab8 also covers a major mutant strand that has evolved since COVID-19 first emerged in China. Because the Ab8 antibody is able to prevent SARS-CoV-2's spike proteins from attacking cells, it's also versatile from virus to virus.

“It's active against a broad range of virus variance,” Mellors said.

Ab8's effectiveness thus far has been found in mice and hamsters. Human trials are expected to begin at the start of 2021.

“The proof is in the human studies,” Mellors said. “Although there's no guarantee, all signs are pointing toward a positive effect.”

“UPMC and Pitt will remain at the forefront of battling this pandemic,” said Dr. Steven Shapiro, UPMC's chief medical and scientific officer. “There's still much work to be done.”

Mellors said he hopes Ab8 will help scientists to understand how to treat a number of virus infections years into the future.

“There are very, very few silver linings (to COVID-19),” Mellors said. “But one of them will be the world will be better prepared ... for other pandemics.”