A Chinese research team has adopted a new strategy to design a new COVID-19 vaccine that has shown to be highly effective in mice and macaques against infections by Delta and Omicron strains.

The team that published this discovery was led by Gao Fu, Director of the Chinese Center for Disease Control and Prevention, Wang Peiyi, professor at the Southern University of Science and Technology, and Dai Lianpan, researcher at the Chinese Academy of Sciences. The team's latest paper, "Protective prototype-Beta and Delta-Omicron chimeric RBD-dimer vaccines against SARS-CoV-2," was included in Cell, a top-ranking biology journal on Tuesday.

The researchers previously developed the protein subunit vaccine ZF2001 based on dimeric receptor-binding domain (RBD) of prototype SARS-CoV-2. In the latest study, the team developed a chimeric RBD-dimer vaccine approach to adapt to SARS-CoV-2 variants.

A prototype-Beta chimeric RBD-dimer was first designed to adapt to the resistant Beta variant. Compared with its homotypic forms, the chimeric vaccine elicited broader sera neutralization of variants and conferred better protection in mice. The protection of the chimeric vaccine was further verified in macaques, according to the researchers.

This approach was generalized to develop a Delta-Omicron chimeric RBD-dimer to adapt to the currently prevalent variants. The vaccine conferred better protection against either Delta or Omicron SARS-CoV-2 in mice.

As breakthrough infections by COVID-19 variants become the global challenge for pandemic control, the chimeric approach is applicable for rapid updating of immunogens. The data supported the use of variant-adapted multivalent vaccine against circulating and emerging variants, the researchers say.

Previously, ZF2001, the world's first approved COVID-19 protein subunit vaccine, was developed and produced from a pre-design concept developed by Gao Fu's team and approved for emergency use in China, Uzbekistan, Indonesia and Colombia.

Recently, vaccine studies by other Chinese research teams have also caught the attention of the international academic community. A circular RNA vaccine reported by Wei Wensheng's team at the Peking University and a nanoparticle vaccine by Zhang Hui's team at the Sun Yat-sen University of Medical Sciences, have both shown to be effective against Omicron in laboratory trials.

Their studies are believed to play a key role in technology leadership in future vaccine development, observers noted.