GAITHERSBURG, Md. (NewsNation Now) — An experimental vaccine to protect against seasonal flu and COVID-19 showed promise in ferrets and hamsters, Novavax announced Monday.

A news release said hamsters were given the company’s standard COVID-19 vaccine and the combo shot showed similar levels of protection when challenged with SARS CoV-2, the virus that causes COVID-19. It said scans of the animals’ lungs showed “no remarkable findings” after infection, regardless of which vaccine they got. The findings said the immune response was stronger after two doses.

The company has been testing its standard COVID-19 vaccine in a Phase 3 trial in North America since December 2020. A Phase 3 trial in the United Kingdom found it was 100% effective against severe disease and had 89.7% efficacy overall, including against various strains.

This hybrid vaccine is in an earlier stage of development. The company’s executive vice president, Russell ‘Rip’ Wilson, said they are looking ahead to a time when COVID-19 vaccines might be available annually, like flu shots.

“Seasonal influenza and COVID-19 combination vaccines will likely be critical to combating emerging COVID-19 variants,” he said. “We expect this combination vaccine will help control both COVID-19 and influenza illness.”

They plan to start clinical studies of the hybrid shot by the end of the year.

The company’s COVID-19 shot is not an mRNA vaccine, as Pfizer and Moderna have pioneered. Novavax uses nanoparticles to create an antigen, a substance your immune system would respond to, based on the COVID-19 spike protein. It does not use a dead or weakened virus, like Johnson & Johnson’s and AstraZeneca’s.

Novavax has touted the success of its flu shot, which it calls NanoFlu, in clinical trials, but the Food and Drug Administration has not yet approved it. Wilson said the shot has “achieved all of its primary endpoints” in its flu-specific Phase 3 trial.