Toward broad-spectrum coronavirus vaccines: navigating viral evolution from past epidemics to future resilience

SUMMARY Newly emerged highly pathogenic coronavirus species, including SARS-CoV, MERS-CoV, and SARS-CoV-2, have successively triggered outbreaks worldwide over the past 25 years. Recently, several MERS-related coronaviruses have been identified from bats or pangolins. These viruses, along with previously found SARS-related coronaviruses, pose significant potential to infect humans and trigger pandemics. Therefore, it is necessary to develop broad-spectrum vaccines that can combat both currently circulating coronaviruses and those that may emerge in the future. Currently, approved COVID-19 vaccines provide strong protection against pre-Omicron variants, while their effectiveness against post-Omicron variants is reduced, and cross-protection against other potential coronaviruses remains limited. In the present review, we discuss vaccine research on SARS-CoV and MERS-CoV prior to the COVID-19 outbreak, as well as vaccine development following the outbreak. We also focus on strategies for developing broad-spectrum coronavirus vaccines and provide a perspective on future directions for coronavirus vaccine development.