Long-term stability and protection efficacy of the RBD-targeting COVID-19 mRNA vaccine in nonhuman primates

Messenger RNA(mRNA)vaccine technology has shown its power in preventing the ongoing COVID-19 pandemic.Two mRNA vaccines targeting the full-length S protein of SARS-CoV-2 have been authorized for emergency use.Recently,we have developed a lipid nanoparticle-encapsulated mRNA(mRNA-LNP)encoding the receptor-binding domain(RBD)of SARS-CoV-2(termed ARCoV),which confers complete protection in mouse model.Herein,we further characterized the protection efficacy of ARCoV in nonhuman primates and the Iong-term stability under normal refrigerator temperature.Intramuscular immunization of two doses of ARCoV elicited robust neutralizing antibodies as well as cellular response against SARS-CoV-2 in cynomolgus macaques.More importantly,ARCoV vaccination in macaques significantly protected animals from acute lung lesions caused by SARS-CoV-2,and viral replication in lungs and secretion in nasal swabs were completely cleared in all animals immunized with low or high doses of ARCoV.No evidenee of antibody-dependent enhancement of infection was observed throughout the study.Finally,extensive stability assays showed that ARCoV can be stored at 2-8℃ for at least 6 months without decrease of immunogenicity.All these promising results strongly support the ongoing clinical trial.

One year of COVID-19 vaccination

The year 2021 saw the development and deployment of COVID-19 vaccines at an unprecedented pace,which is a remarkable success in science and technology.COVID-19 vaccines based on different technology platforms have been given to billions of humans globally to minimize the infection and transmission of SARS-CoV-2,and most importantly,to end the COVID-19 pandemic.Here,we provide a snapshot of the current status and future challenge of COVID-19 vaccination after one year.

Anti-viral memory T cell responses in the absence of IgG production in a COVID-19 convalescent individual

Cellular and humoral immunity are both important in host defense against severe acute respiratory syndrome coronavirus 2(SARS-CoV-2).Although defects in SARS-CoV-2-specific T cell immunity have been found in patients with severe lung pathology,it is still largely unclear whether virus-specific T cells are sufficient for host protection.Here,we found that in a previously characterized cohort of convalescent subjects,one individual,though lacking detectable anti-viral neutralizing IgG antibodies,showed virus-specific T cell responses,both in CD4^(+)and CD8^(+)T cells.SARS-CoV-2-specific T cells in this and other individuals are maintained for up to 10 months.This study thus further supports a critical role of T cells in host defense against SARS-CoV-2,offering new insights into the design and evaluation of COVID-19 vaccines.

Longitudinal dynamics of antibody responses in recovered COVID-19 patients

Dear Editor,The coronavirus disease 2019(COVID-19)has resulted in more than 66.5 million cases globally in more than 191 countries with overl,529,000 mortalities as of 6 December.Currently,the COVID-19 continued to spread around the world,while the duration of antibody lasts and antibody level remained poorly understood,which are primary for safe and effective antiviral treatments and vaccines in the future.In this study,we comprehensively characterized the longitudinal changes of antibodies in recovered patients from 5-7 to 34-42 weeks after symptom onset.