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SAN DIEGO — Researchers in San Diego are working on a new type of coronavirus vaccine that appeared to work well against emerging COVID-19 variants in initial trials on mice.

Scientists at Scripps Research said unlike most COVID-19 vaccines that instruct the body to create individual “spikes” from the virus, the new vaccine delivers the spikes on tiny sphere-shaped proteins. They’re meant to mimic the real shape of the virus and trick the body into producing stronger immune protection.

Scripps Research said results from testing the experimental COVID-19 vaccine on mice suggest the protein-based vaccine could serve as a booster shot to cover emerging variants. The vaccine appeared to work well against three variants of concern—known as B.1.1.7, B.1.351 and P.1.

The variants have spread widely in recent months, especially in the UK, South Africa, Brazil and Europe. Local health leaders announced two cases of the P.1 variant were detected in San Diego County last week. Preliminary evidence suggests some or all of the variants may be less susceptible to COVID-19 vaccines now in use.

Dr. Jiang Zhu is the scientist behind the experimental vaccine. Scripps Research said Zhu and colleagues found evidence in a previous study that their whole-virus-mimicking approach stimulated a stronger immune response than spikes alone. They confirmed those findings with new experiments in the latest study.

“The effectiveness of our vaccine against new variants in this preclinical study is exciting, as are some of the ‘firsts’ we achieved in vaccine immunology,” Zhu said. “For example, we were able to directly image our vaccine particles in the lymph node tissues of inoculated mice, capturing the start of the antibody response.”

Scripps Research said the team is now working toward a clinical trial in the near future.