Moraxella occupied the largest proportion in the nasal microbiome in healthy children, which potential protect them from COVID-19.

BACKGROUND: In the prevalence of COVID-19, infection symptoms are different in children and adults. In this study to investigate the differences in the upper respiratory tract microbiome profile between healthy children and adults and to explore which microbiome protect them from COVID-19. METHODS: Thirty healthy children and 24 healthy adults were enrolled between October 2020 and January 2021. Nasal and throat swabs were obtained at enrollment, and DNA was extracted. We performed 16S rDNA sequencing to compare the alpha and beta diversity of the nasal and throat microbiomes between children and adults and assessed potential microbiome biomarkers. RESULTS: In the nasal microbiome, there were significant differences between healthy children and adults, and Moraxella occupied the largest proportion in healthy children. Notably, there was no significant difference between healthy children and adults in the throat microbiome, and it was predominated by Firmicutes. In the function analysis, compared with adults, there was increased enrichment in pathways related to amino acid metabolism and lipid metabolism, in children. CONCLUSIONS: In the upper respiratory tract microbiome profiles, Moraxella may be involved in protecting children from COVID-19 infections and may be involved the amino acid metabolism and lipid metabolism.

Recent Advances in Delivery Systems for Genetic and Other Novel Vaccines.

Vaccination is one of the most successful and cost-effective prophylactic measures against diseases, especially infectious diseases including smallpox and polio. However, the development of effective prophylactic or therapeutic vaccines for other diseases such as cancer remains challenging. This is often due to the imprecise control of vaccine activity in vivo which leads to insufficient/inappropriate immune responses or short immune memory. The development of new vaccine types in recent decades has created the potential for improving the protective potency against these diseases. Genetic and subunit vaccines are two major categories of these emerging vaccines. Owing to their nature, they rely heavily on delivery systems with various functions, such as effective cargo protection, immunogenicity enhancement, targeted delivery, sustained release of antigens, selective activation of humoral and/or cellular immune responses against specific antigens, and reduced adverse effects. Therefore, vaccine delivery systems may significantly affect the final outcome of genetic and other novel vaccines and are vital for their development. This review introduces these studies based on their research emphasis on functional design or administration route optimization, presents recent progress, and discusses features of new vaccine delivery systems, providing an overview of this field.