CONCLUSION
This case-control study confirmed that full or booster vaccination of three types of vaccines was able to provide limited protection against Omicron variant infection, although the VE of each type of vaccine showed slightly different results. There was substantially increased protection from the booster vaccination (homologous and heterologous booster vaccinations) against the Omicron variant infection compared with full vaccination. Moreover, heterologous booster vaccination conferred better protective immunity against the Omicron variant than homogenous booster vaccination. The adjusted VEs of the recombinant protein vaccine were slightly lower than those of other COVID-19 vaccines against the Omicron variant infection. A vaccination campaign for a booster dose is urgent to be conducted after three doses of recombinant protein vaccine urgently needs to be conducted and requires further observation.