Centers for Disease Control and Prevention (CDC): https://www.cdc.gov/

National Institutes of Health (NIH): https://www.nih.gov/

Mayo Clinic: https://www.mayoclinic.org/

WebMD: https://www.webmd.com/

PubMed – National Library of Medicine: https://pubmed.ncbi.nlm.nih.gov/

Harvard Health Publishing: https://www.health.harvard.edu/

MedlinePlus: https://medlineplus.gov/

European Centre for Disease Prevention and Control (ECDC): https://www.ecdc.europa.eu/

Johns Hopkins Medicine: https://www.hopkinsmedicine.org/

World Health Organization (WHO): https://www.who.int/