Research and application progress of COVID-19 vaccine

The coronavirus disease 2019 (COVID-19) pandemic is a serious threat to human life, health and social development. In response to this public health event, various COVID-19 vaccines have been rapidly developed around the world. To date, 41 vaccines have been approved for emergency use, and the use of vaccines has significantly reduced the morbidity and mortality of COVID-19. However, with the continuous mutants, especially the emergence of the Omicron variant, challenges to vaccine-induced immune protection are appearing, there is still a long way to go for the continued development of COVID-19vaccines. This article briefly reviews the research progress of COVID-19 vaccine and its effect on mutant virus strains.

Etiology, clinical features, infection control and therapy of SARS-CoV-2 Omicron variant

The Omicron variant of SARS-CoV-2 is a new variant of concern after Alpha, Beta, Gamma and Delta variants. The amino acid mutations in the viral antigens, especially in the receptor binding region (RBD) of spike protein, were significantly more than those of other variants, which lead to the significant increase of infectivity, transmissibility and immune escape of Omicron variant. In addition, those spike mutations impaired the protective effect of vaccination. When compared to the infection of other variants, the latency of Omicron variant infection was significantly shortened, and the pathogenicity decreased markedly, which is in consistence with the fact that the vast majority of infected individuals showed no symptoms or only mild disease. Exacerbations in patients infected by Omicron variant were often associated with the progress of underlying disease. Early detection and medical isolation of infected persons, careful personal protection measures to cut off transmission routes, and active vaccination to protect susceptible people are key measures to prevent the spread of Omicron variant epidemic. A small number of patients infected with Omicron variant may develop so-called long COVID-19, post-COVID-19 syndrome, or post-COVID-19 condition, which means that long-term follow-up is needed in those patients. Effective anti-Omicron variant therapy can shorten the course of infection, promote the recovery from infection, and also contribute to the control of infection. Therefore, the development of antiviral drugs with ideal cost-benefit ratio and convenient administration is one of the research hotspot in the future.