Impact of China's COVID-19 prevention and control efforts on outbreaks of influenza.

The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in a serious public health burden. As the COVID-19 epidemic in China would coincide with a seasonal outbreak of influenza, there were serious concerns about whether influenza would be aggravated by the SARS-CoV-2 infection and COVID-19 pandemic. This article provides a brief overview of the impacts of the COVID-19 epidemic on influenza activity in China. The percentage of positive influenza tests decreased during the COVID-19 pandemic. During the first stage of the COVID-19 outbreak, the percentage of positive influenza tests reached to a peak of 47.7%. At the second stage, the percentage of positive influenza tests was dramatically decreased from 40.4% to 14.0%. Thereafter, it remains at a low level of less than 6.2%. In addition, the possible causes of this phenomenon have been summarized, including prevention and control measures and ecological competition. Lastly, this article suggests that the public health approach to preventing COVID-19 may also help to control other respiratory infectious diseases. Public health measures need to be maintained even in the later stages of the COVID-19 epidemic.

[Population dynamics and antagonism toward Fusarium oxysporium f. sp. Vasinfectum. and Verticillium dahliae Kleb of endophytic bacteria from cotton].

OBJECTIVE: To explore population dynamics of endophytic bacteria and obtain antagonistic endophytic bacteria toward Verticillium dahliae Kleb (Vd), Fusarium oxysporium f. sp. Vasinfectum (Fov) from cotton. METHODS: Root, stem and leaf samples were surface-disinfested, and subsequently used to isolate endophytic bacteria by diluting plate counting method. We assayed antagonism of the isolated endophytic bacteria toward three pathogens: Vd (V107, which is a highly virulent defoliating isolate and V396, which is a mildly virulent non-defoliating isolate), Fov (F108) using a dual culture method, and analyzed the 16S rDNA sequence of doubly antagonistic endophytic bacteria (DAEB) isolates toward both Vd and Fov. RESULTS: The population size of endophytic bacteria in root was significantly larger than that in leaf and stem. The populations at seedling stage were generally lower than those at the flowering/maturing stage in root, the populations in stem and leaf were fluctuant at different development stages, but variation law was not observed obviously. Furthermore, although no significant differences of the population densities in root were found among 6 cotton cultivars, the population densities in stem and leaf showed cultivar differences. The proportion of endophytic bacteria antagonizing Vd (V107, V396) and Fov (F108) in root was higher than that in stem/leaf, moreover, the amount of endophytic bacteria antagonizing toward V107 was less than that toward V396/F108. Based on 16S rDNA sequence analysis, all 44 DAEB isolates consisted of two phyla, i.e., Bacteroidetes (1 out of 44) and Proteobacteria (43 out of 44), and fell into 8 genera. The genus enterobacter (18 out of 44) and Pantoea (15 out of 44) were predominant. Notably, ten DAEB isolates demonstrated <97% sequence similarity with the most similar sequences of strain deposited in the Ribosomal Database, these DAEB isolates might be potential novel species. CONCLUSION: This article suggested that plant genotype, development stage, and tissue influenced the population of endophytic bacteria. We discovered that DAEB with predominant and various genus existed in cotton. Endophytic bacteria in cotton could serve as a pool for discovering biocontrol agent toward cotton pathogens.