ABSTRACT
Social distancing has been essential during the COVID-19 pandemic to slow the spread of the disease. Online learning ensures students can participate in learning activities while also maintaining a physical distance from other students. Although online learning was used to prevent the spread of COVID-19, the development of online learning has also been promoted. Here, we sought to explore the perceptions and responses of students to online learning during the pandemic using a cross-sectional study. Electronic questionnaire was used for data collection. Statistical analyses were performed for 1614 valid questionnaires and P < 0.05 was considered statistically significant. Overall, COVID-19 had more effect on female students, such as fear of COVID-19 (2.4 times higher than the number of male students) and length of time spent learning (H = 42.449, P < 0.05). However, the higher the students' grades were, the less the impact of COVID-19. For the style of lessons, all students would prefer shorter lessons (P < 0.05). Female and fifth-grade students were more prefer combined online and face-to-face learning, and male and freshmen students were more likely to prefer face-to-face learning after the pandemic. More than 50% of students thought the main advantage of online learning was convenience, with low efficiency being a disadvantage. The main factors negatively influencing online learning were eyestrain, poor network connections, and poor learning environments at home. In conclusion, synchronous online and face-to-face learning may become more common in future curricula, however the efficiency of online learning and the female students more attentions.
ABSTRACT
Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19) pandemic. In this study, we conducted a comparative analysis of the structural genes of SARS-CoV-2 and other CoVs. We found that the sequence of the E gene was the most evolutionarily conserved across 200 SARS-CoV-2 isolates. The E gene and M gene sequences of SARS-CoV-2 and NC014470 CoV were closely related and fell within the same branch of a phylogenetic tree. The absolute diversity of E gene and M gene sequences of SARS-CoV-2 isolates was similar to that of common CoVs (C-CoVs) infecting other organisms. The absolute diversity of the M gene sequence of the KJ481931 CoV that can infect humans was similar to that of SARS-CoV-2 and C-CoVs infecting other organisms. The M gene sequence of KJ481931 CoV (infecting humans), SARS-CoV-2 and NC014470 CoV (infecting other organisms) were closely related, falling within the same branch of a phylogenetic tree. Patterns of variation and evolutionary characteristics of the N gene and S gene were very similar. These data may be of value for understanding the origins and intermediate hosts of SARS-CoV-2.
ABSTRACT
The pandemic COVID-19 is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and it is spreading very rapidly worldwide. To date, the origin and intermediate hosts of SARS-CoV-2 remain unclear. In this study, we conducted comparative analysis among SARS-CoV-2 and non-SARS-CoV-2 coronavirus strains to elucidate their phylogenetic relationships. We found: 1, the SARS-CoV-2 strains analyzed could be divided into 3 clades with regional aggregation; 2, the non-SARS-CoV-2 common coronaviruses that infect humans or other organisms to cause respiratory syndrome and epizootic catarrhal gastroenteritis could also be divided into 3 clades; 3, the hosts of the common coronaviruses closest to SARS-CoV-2 were Apodemus chevrieri (a rodent), Delphinapterus leucas (beluga whale), Hypsugo savii (bat) , Camelus bactrianus (camel) and Mustela vison (mink); and 4, the gene sequences of the receptor ACE2 from different hosts could also be divided into 3 clades. The ACE2 gene sequences closest to that of humans in evolution include those from Nannospalax galili (Upper Galilee mountains blind mole rat), Phyllostomus discolor (pale spear-nosed bat), Mus musculus (house mouse), Delphinapterus leucas (beluga whale), and Catharus ustulatus (Swainson's thrush). We conclude that SARS-CoV-2 may have evolved from a distant common ancestor with the common coronaviruses but not a branch of any of them, implying that the prevalent pandemic COVID-19 agent SARS-CoV-2 may have existed in a yet to be identified primary host for a long time.