The discovery and development of mRNA vaccines for the prevention of SARS-CoV-2 infection.

INTRODUCTION: COVID-19 pandemic is one of the most serious public health events of this century. There have been more than 670 million confirmed cases and more than 6 million deaths worldwide. From the emergence of the Alpha variant to the later rampant Omicron variant, the high transmissibility and pathogenicity of SARS-CoV-2 accelerate the research and development of effective vaccines. Against this background, mRNA vaccines stepped onto the historical stage and became an important tool for COVID-19 prevention. AREAS COVERED: This article introduces the characteristics of different mRNA vaccines in the prevention of COVID-19, including antigen selection, therapeutic mRNA design and modification, and different delivery systems of mRNA molecules. It also summarizes and discusses the mechanisms, safety, effectiveness, side effects, and limitations of current COVID-19 mRNA vaccines. EXPERT OPINION: Therapeutic mRNA molecules have plenty of advantages, including flexible design, rapid production, sufficient immune activation, safety without the risk of genome insertion in the host cells, and no viral vectors or particles involved, making them an important tool to fight diseases in the future. However, the application of COVID-19 mRNA vaccines also faces many challenges, such as storage and transportation, mass production, and nonspecific immunity.

The clinical characteristics of pediatric patients infected by SARS-CoV-2 Omicron variant and whole viral genome sequencing analysis.

Pediatric population was generally less affected clinically by SARS-CoV-2 infection. Few pediatric cases of COVID-19 have been reported compared to those reported in infected adults. However, a rapid increase in the hospitalization rate of SARS-CoV-2 infected pediatric patients was observed during Omicron variant dominated COVID-19 outbreak. In this study, we analyzed the B.1.1.529 (Omicron) genome sequences collected from pediatric patients by whole viral genome amplicon sequencing using Illumina next generation sequencing platform, followed by phylogenetic analysis. The demographic, epidemiologic and clinical data of these pediatric patients are also reported in this study. Fever, cough, running nose, sore throat and vomiting were the more commonly reported symptoms in children infected by Omicron variant. A novel frameshift mutation was found in the ORF1b region (NSP12) of the genome of Omicron variant. Seven mutations were identified in the target regions of the WHO listed SARS-CoV-2 primers and probes. On protein level, eighty-three amino acid substitutions and fifteen amino acid deletions were identified. Our results indicate that asymptomatic infection and transmission among children infected by Omicron subvariants BA.2.2 and BA.2.10.1 are not common. Omicron may have different pathogenesis in pediatric population.

Whole genome amplicon sequencing and phylogenetic analysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from lineage B.1.36.27 isolated in Hong Kong.

BACKGROUND: The import of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineage B.1.36.27 has sparked the fourth wave of COVID-19 outbreak in Hong Kong. This strain has been circulating in Hong Kong since September 2020 but rarely found in other countries (<1%). RESEARCH DESIGN AND METHODS: A total of 14 SARS-CoV-2 genome sequences collected from patients in Hong Kong between July 2020 and March 2021 were determined by whole viral genome sequencing using Illumina next-generation sequencing platform, followed by phylogenetic analysis. RESULTS: Of the 14 SARS-CoV-2 genome sequences analyzed, 9 strains belonged to the PANGO lineage B.1.36.27, GISAID clade GH, and Nextclade clade 20A. Compared to the reference genome, 31 nucleotide differences and 11 amino acid differences were identified in the genome of the SARS-CoV-2 from PANGO lineage B.1.36.27. CONCLUSIONS: We reported the nucleotides and amino acids mutations identified in the SARS-CoV-2 from PANGO lineage B.1.36.27. Our viral genome sequences enriched the understanding of SARS-CoV-2 mutational landscape and improved the repertoire of known SARS-CoV-2 variants for tracking and tracing. From this study, we found no evidence to show that SARS-CoV-2 from lineage B.1.36.27 can compromise existing vaccines and antibody therapies.

Performance comparison of the Cobas® Liat® and Cepheid® GeneXpert® systems on SARS-CoV-2 detection in nasopharyngeal swab and posterior oropharyngeal saliva.

Background: Nucleic acid amplification tests (NAATs) based methods such as real-time reverse transcription polymerase-chain reaction (real-time RT-PCR) are the gold standard for diagnosis of current infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The cobas® Liat® and cepheid® GeneXpert® systems are two rapid real-time RT-PCR platforms offering rapid, specimen-to-answer detection of SARS-CoV-2.Research design and methods: In this study, we compared the performance of these two systems on SARS-CoV-2 detection in 9 nasopharyngeal swab (NPS) and 70 posterior oropharyngeal saliva specimens collected from 79 patients suspected of SARS-CoV-2 infection between August 2020 and March 2021.Results: The Positive Percent Agreement (PPA), Negative Percent Agreement (NPA) and overall Percent Agreement (OPA) between cepheid® Xpress SARS-CoV-2 assay and cobas® Liat® SARS-CoV-2 & Influenza A/B assay were found to be 100%. We demonstrated an excellent overall test concordance of the Liat® SARS-CoV-2 & Influenza A/B assay and Xpress SARS-CoV-2 assay. The small sample size of SARS-CoV-2 positive and weak-positive specimens is the inherent limitation of this study.Conclusions: The performance of the cobas® Liat® SARS-CoV-2 & Influenza A/B assay is equivalent to the cepheid® Xpress SARS-CoV-2 assay for SARS-CoV-2 detection using NPS and posterior oropharyngeal saliva.

An update on COVID-19 pandemic: the epidemiology, pathogenesis, prevention and treatment strategies.

INTRODUCTION: To date, the transmission of Coronavirus Disease-2019 (COVID-19) is still uncontrollable with the fact that the numbers of confirmed and death cases are still increasing. Up to 1st October 2020, 33,842,281 confirmed cases and 1,010,634 confirmed deaths have been reported to the World Health Organization from 216 different countries, areas and territories. Despite the urgent demand for effective treatment strategies, there is still no specific antiviral treatment for COVID-19 and the treatment guidelines for COVID-19 vary between countries. AREA COVERED: In this article, we summarized the current knowledge on COVID-19 and the pandemic worldwide. Moreover, the epidemiology, pathogenesis, prevention and different treatment options will be discussed so that we shall prepare ourselves better to fight with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). EXPERT OPINION: The situation of the COVID-19 pandemic is still unpredictable. There is no effective vaccine or specific anti-viral drug to treat serve COVID-19 patients. Combination therapies have shown promising clinical improvement. Repurposing FDA-approved drugs might be one of possible treatment options. Without specific treatment and vaccines for COVID-19, the most effective way to prevent from being infected is to generate an ecosystem with effective protection, precautions and preventive measures.

The diagnostic methods in the COVID-19 pandemic, today and in the future.

INTRODUCTION: The emergence of anovel coronavirus identified in patients with unknown cause of acute respiratory disease in Wuhan, China at the end of 2019 has caused aglobal outbreak. The causative coronavirus was later named as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the disease caused by SARS-CoV-2 was named as Coronavirus Disease-2019 (COVID-19). As of 10 August 2020, more than 19,718,030 confirmed cases and 728,013 deaths have been reported. COVID-19 is spread via respiratory droplets which are inhaled into the lungs. AREAS COVERED: In this article, we summarized the knowledge about the causative pathogen of COVID-19 and various diagnostic methods in this pandemic for better understanding of the limitations and the nuances of virus testing for COVID-19. EXPERT OPINION: In this pandemic, rapid and accurate identification of COVID-19 patients are critical to break the chain of infection in the community. RT-PCR provides a rapid and reliable identification of SARS-CoV-2 infection. In the future, molecular diagnostics will still be the gold standard and next-generation sequencing can help us to understand more on the pathogenesis and detect novel mutations. It is believed that more sophisticated detection methods will be introduced to detect SARS-CoV-2 as earliest as possible.