In theory, viral\vector vaccines can also induce multiple immune responses

In theory, viral\vector vaccines can also induce multiple immune responses. diagnosis, prevention, and treatment of COVID\19, efforts should be made to explore new biocompatible nano\biomaterials to advance this field to clinical applications. Hence, nanobiotechnology paves a new way to detect, prevent, and treat COVID\19 effectively. value can change over time. The was estimated to be between 2.0 and 3.0 for SARS and around 0.69 for MERS. 17 , 18 For SARS\CoV\2, the was preliminarily reported as 2.24C3.58. 19 Due to the different stages of the epidemic and unique estimation methods, several different values of SARS\CoV\2 were reported. In February 2020, Liu et?al. estimated the average to be 3.28 and median to be 2.79 using stochastic and statistical methods. 20 In clinical studies, Yang et?al. surveilled 4021\cases of COVID\19 recognized before January 26, 2020, and reported an of approximately 3.77. 21 COVID\19 has been characterized as a type of self\limiting infectious disease, and this disease can occur in five different patterns. The first pattern is asymptomatically infected people without any symptom or clinical sign. The second pattern is mild to medium cases with mild upper respiratory tract symptoms or pneumonia. The third pattern is severe cases with severe pneumonia requiring oxygen administration. The fourth pattern is critical cases with acute respiratory distress syndrome (ARDS) or other acute symptoms such as shock and respiratory failure. The fifth pattern is death. From initial exposure to an infectious agent to the onset of any symptoms, this interval is called the incubation period. A long incubation period may contribute to a high rate of subclinical and asymptomatic infection. The mean incubation period of COVID\19 is between 4 and 7 days, and an unusual 19\days incubation A1874 case was also reported. 22 Considering the 19\days incubation period is a small probability event, the maximum quarantine time was suggested as 14 days. The COVID\19 infected person is the main source of infections. The person\to\person transmission can occur in several different ways, including contact and droplet transmission, 5 , 14 , 24 , 25 airborne ITGA2 transmission, 26 A1874 , 27 , 28 , 29 and fomite transmission. 30 , 31 , 32 Additionally, SARS\CoV\2 RNA detected A1874 by reverse transcription polymerase chain reaction (RT\PCR) can also be found in other biological samples, including plasma, serum, urine, and feces. Some studies reported that SARS\CoV\2 was cultured from stool specimens. 33 The existence of viable SARS\CoV\2 in the urine sample 34 and blood cells is also reported. Due to limited data, the role of SARS\CoV\2 transmission through these routes remains uncertain. 4.?DETECTION OF COVID\19 Early and accurate diagnosing is crucial to control the spread of COVID\19. The symptoms of COVID\19 include fever, cough, fatigue, sputum production, and shortness of breath, which are similar to other respiratory infections. 35 Therefore, syndromic testing is not suitable for accurate detection and screening of COVID\19. The current diagnostic A1874 tests include biomarkers detections and imaging detections. 4.1. Biomarkers detections Detection of COVID\19 by biomarkers relies on molecular techniques to target and identify specific biomarkers. The biomarkers of SARS\CoV\2 mainly involve nucleic acid and viral proteins. Compared with the detection of viral protein, nucleic acid testing has been applied more widely to the accurate diagnosis of COVID\19 in the clinic. At the initial outbreak of the COVID\19 pandemic, the full genome of the causative agent (SARS\CoV\2) was identified using the combination of RT\PCR and metagenomic next generation sequencing (NGS). 36 , 37 , 38 Thereby, infectious cases can be confirmed using genome sequencing. However, this strategy is costly, time\consuming, and labor\intensive. Many RT\PCR test kits have been developed to solve these problems with the increased understanding of viral genomic composition. Since the first report of the full SARS\CoV\2 genome published on January 7, 2020, there have been many released SARS\CoV\2 sequences under the GISAID. 37 These data are bedrocks for the development of RT\PCR or another nucleic acid testing. Up to now, RT\PCR detection is predominantly used for molecular diagnosis of COVID\19. The National Medical Products Administration has approved more than 10 nucleic acid testing methods for detecting COVID\19 in China. An accurate diagnosis using RT\PCR needs sufficient preliminary work, including the collection and treatment of specimens, sequence alignment, primer design, and assay optimization. In the diagnosis of COVID\19, respiratory specimens are usually collected because they have the highest viral loads of SARS\CoV\2 A1874 and highest positive rates of RT\PCR testing compared with other types of clinical specimens such as blood, stool, and urine. 39 Respiratory specimens can be divided into upper respiratory specimens and lower respiratory specimens. The upper respiratory specimens include nasopharyngeal and oropharyngeal swabs, as well as nasopharyngeal and endotracheal washes. The lower respiratory specimens include bronchoalveolar lavage, endotracheal aspirate, and sputum. Nasopharyngeal swabs are generally collected to detect.