There is an urgent need for vaccines against coronavirus disease 2019 (COVID-19) because of the ongoing SARS-CoV-2 pandemic. Among all approaches, a messenger RNA (mRNA)-based vaccine has emerged as a rapid and versatile platform to quickly respond to this challenge. Here, we developed a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor binding domain (RBD) of SARS-CoV-2 as a vaccine candidate (called ARCoV). Intramuscular immunization of ARCoV mRNA-LNP elicited robust neutralizing antibodies against SARS-CoV-2 as well as a Th1-biased cellular response in mice and non-human primates. Two doses of ARCoV immunization in mice conferred complete protection against the challenge of a SARS-CoV-2 mouse-adapted strain. Additionally, ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week. ARCoV is currently being evaluated in phase 1 clinical trials.

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Background:Ultrasound is used to observe the imaging manifestations of COVID-19 in order to provide reference for real-time bedside evaluation.Purpose: To explore the ultrasonic manifestations of peripulmonary lesions of non-critical COVID-19, so as to provide reference for clinical diagnosis and efficacy evaluation. Materials and Methods: The clinical and ultrasonic data of 20 patients with clinically diagnosed non-critical COVID-19 treated in Xi'an Chest Hospital during January and February 2020 were retrospectively analyzed. Conventional two-dimensional ultrasound and color Doppler ultrasound were used to observe the characteristics of lesions. Results: All 20 patients (40 lungs and 240 lung areas) had a history of travel, residence or close contact in/with Wuhan, and 5 of them caught COVID-19 after family gatherings. Lesions tended to occur in both lungs. Lesions in the lung areas: 14 in L1+R1 area (14/40), 17 in L2+R2 area (17/40), 17 in L3+R3 area (17/40), 17 in L4+R4 area (17/40), 20 in L5+R5 area (20/40), and 28 in L6+R6 area (28/40). Lesion types: rough and discontinuous pleural line (36/240), subpleural consolidation (53/240), air bronchogram sign or air bronchiologram sign in subpleural peripleural consolidation (37/240), visible B lines (91/240), localized pleural thickening (19/240), localized pleural effusion (24/240), poor blood flow in the consolidation detected by color Doppler ultrasound (50/53). Conclusion: The non-critical COVID-19 has characteristic ultrasonic manifestations, which are visible in the posterior and inferior areas of the lung. The lesions are mainly characterized by a large number of B lines, subpleural pulmonary consolidation and poor blood flow. Lung ultrasound can provide reference for the clinical diagnosis and efficacy evaluation.