CAS-TWAS Centre of Excellence for Biotechnology(CoEBio) and the Polymer Institute of Nepal jointly held the online conference "3rd International Conference on infectious Diseases and Nanomedicine-2021" (ICIDN-2021) from December 15 to 18, 2021. There were more than 300 scholars from 18 developing and developed countries and regions, including China, the United States, Nepal, India, Iran, Mongolia, South Africa, the United Kingdom, Canada participated in the conference online. COVID-19 epidemic, vaccine research and development, application of nanoparticles and the role of human microbiome in health and disease were discussed on the meeting. Two thirds of the participants are postgraduates and postdoctors from developing countries. This seminar has created a valuable opportunity for those young scientists to learn and communicate with international experts.