Global research on Coronavirus disease (COVID-19) - WHO is gathering the latest scientific findings and knowledge on coronavirus disease (COVID-19) and compiling it in a database. They update the database everyday by searching bibliographic databases, the table of contents of relevant journals, and adding other relevant scientific articles. New research is being added regularly.
LitCovid - LitCovid is a curated literature hub for tracking up-to-date scientific information about the 2019 novel Coronavirus. It is the most comprehensive resource on the subject, providing a central access to growing relevant articles in PubMed. The articles are updated daily and are further categorized by different research topics and geographic locations for improved access.
https://www.ncbi.nlm.nih.gov/research/coronavirus/
Elsevier's Novel Coronavirus Information Center - provides latest early-stage and peer-reviewed research on COVID-19 from journals including The Lancet and Cell Press.There are nearly 20,000 related articles free to access on ScienceDirect.
https://www.elsevier.com/connect/coronavirus-information-center
Cochrane Special Collections on COVID-19
https://www.cochranelibrary.com/collections/doi/SC000039/full
New England Journal of Medicine -2019 Novel Coronavirus (2019-nCoV) - A collection of articles and other resources on the 2019 Novel Coronavirus outbreak, including clinical reports, management guidelines, and commentary.
https://www.nejm.org/coronavirus
JAMA Network COVID-19 collection
https://jamanetwork.com/journals/jama/pages/coronavirus-alert
European Respiratory Society has published information and resources on COVID-19.
Google Scholar provides access to Covid-19 Literature. Some are free and others may require subscription to the journals.