Statistical analysis Categorical variables were described as frequency and percentage, and continuous variables were shown as mean and standard deviation or median and interquartile range (IQR), as appropriate. the clinical characteristics and vaccination info of all individuals and measured the NAb and anti-S1 (spike protein)?+?N (nucleocapsid protein) IgG-binding antibodies against SARS-CoV-2 in serum samples of Omicron variant-infected individuals at admission, and individuals with WT COVID-19 illness from the time of admission and discharge, and one-year to two-years follow-ups. Results Our results shown higher NAb levels, fewer medical symptoms, and faster viral dropping in Omicron variant infected individuals vaccinated with the booster dose. Cross immunity (natural illness plus vaccination) induces higher NAb levels than vaccine-only immunity. NAb and IgG levels decreased significantly at one-year follow-up in WT convalescents with natural illness. The NAb and IgG levels in booster-vaccinated COVID-19 individuals were higher than those in two-dose-vaccinated individuals. Summary Our results suggest that booster vaccinations are required to improve the level of protective NAbs. Moreover, our data provide important evidence for vaccination strategies based on existing vaccines. Keywords: Omicron variant, Crazy Type, COVID-19, Neutralizing antibody, Vaccine 1.?Intro Coronavirus disease 2019 (COVID-19) continues to spread worldwide, with more than 681 million cases reported as of March 2023 (https://www.worldometers.info/coronavirus). The emergence of the highly transmissible Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), which 1st reported in South Africa in November 2021, sparked an unprecedented wave of COVID-19 instances [1]. The Omicron variant offers more than 30 mutations in the spike protein compared to the ancestral strain, and a strong ability to evade both, vaccine- and infection-induced neutralizing antibody (NAb) response [2], [3], [4], [5]. Currently, vaccination remains the only effective way to control SARS-CoV-2 transmission and the Glucagon receptor antagonists-1 adverse effects of COVID-19 [6]. However, whether vaccination can maintain the immune memory to protect healthy individuals from severe diseases caused by the new SARS-CoV-2 variants is has become an important center of medical discussion. Several studies possess indicated that vaccination can only confer 6C8?weeks of protective immunity against severe disease and death [7], [8]. Numerous studies on COVID-19 vaccines and NAb activity have shown that vaccine-induced NAb titers against Omicron are low and decrease over time. A major cause of breakthrough infections may be long term duration between vaccine Glucagon receptor antagonists-1 doses especially when antibody titers are waning and reduced recognition effectiveness of vaccine-induced NAb due to Glucagon receptor antagonists-1 the Omicron antigenic mutations [9]. The Omicron variant has been reported to exhibits significant immune evasion compared to additional variants, but antibody neutralization is largely restored by vaccine booster doses, protecting against severe COVID-19. Therefore, steps to induce higher levels of NAb are of great significance. In this study, we assessed the effectiveness of booster vaccination against the SARS-CoV-2 Omicron variant and a two-year longitudinal antibody study against wild-type (WT) convalescents, providing important evidence for vaccination strategies based on existing vaccines. 2.?Materials and methods 2.1. Participants We enrolled 301 individuals with confirmed COVID-19 based on SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) test of nasopharyngeal, oropharyngeal, or sputum specimens, who were hospitalized at Taizhou General public Health Medical Center from January 17, 2020 to March 10, 2020, and from March 29, 2022 to April 18, 2022. Out of these, we excluded 139 individuals (82/157 Omicron variant and 57/144?wt cohorts, respectively) with incomplete data. Finally, 162 individuals (75 with the omicron variant and 87 with the WT) were included in this study (Fig. 1 ). Open in a separate window Fig. 1 Circulation chart of the study. COVID-19, Coronavirus disease 2019; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; NAb, neutralizing antibody. We collected individuals information about demographics, medical symptoms, comorbidities, radiologic characteristics, laboratory data, days since 1st sign onset to admission and discharge, vaccination time, vaccination doses, manufacturer, and sampling time (Fig. 2 ). All individuals with WT and Omicron variant experienced received two doses (28?days apart) Sinovac CoronaVac COVID-19 vaccine or the Sinopharm’s Beijing Bio-Institute of Biological Products Coronavirus Vaccine (BBIBP-CorV) of 4?g dose of -propiolactone-inactivated, aluminium hydroxide-adjuvanted COVID-19 vaccine, followed by a third booster dose 7?months after the two initial doses. The vaccine is a 0.5?mL dose containing 600 SU of inactivated SARS-CoV-2 computer virus. To prepare the vaccine, SARS-CoV-2 (CN02 strain) was propagated in African green monkey kidney cells (WHO Vero 10C87 Cells). Open in a separate window Fig. 2 Rabbit Polyclonal to CCR5 (phospho-Ser349) Experimental format and patient cohort. Patient baseline info.