Natural Infection of Omicron BA.5.2 in Patients Provides Broad Immune Responses Against SARS-CoV-2.

The implementation of COVID-19 policy and the rapid development of SARS-CoV-2 vaccines in the early pandemic significantly contained numerous outbreaks and reduced the severity and mortality of COVID-19. However, the population immunity induced by existing vaccines was insufficient to prevent SARS-CoV-2 outbreaks. The host immunity induced by the wide spread of Omicron variants and its influence on emerging SARS-CoV-2 variants are attracting broad attention. In this study, a clinical data analysis of the patients indicated that pre-vaccination reduced inflammatory responses and mitigated the severity of COVID-19 cases caused by natural infection with Omicron BA.5.2. The analysis of adaptive immune responses indicated that natural infection with BA.5.2 induced robust and broad immune responses, including both humoral and T cell-mediated immune responses (IFN-γ) against highly conserved viral antigens, and provided cross-reactive neutralization against various viral variants. Collectively, we report that the natural infection with Omicron BA.5.2 induced broad cross-reactive immunity against SARS-CoV-2 variants, which suggests that the development of a live attenuated SARS-CoV-2 vaccine with desired safety, high efficacy, broad spectrum, and long-term immune persistence is feasible. Therefore, we suggest that herd immunity, achieved through vaccination with attenuated vaccines, combined with booster doses of existing vaccines and antiviral therapy for people with high viral loads, may contribute to the eradication of this virus.