US Center for Disease Control and Prevention
https://www.cdc.gov/coronavirus/2019-ncov/index.html

European Centre for Disease Prevention and Control
https://www.ecdc.europa.eu/en/covid-19-pandemic

Institute for Health Metrics and Evaluation (IHME) - an independent global health research center at the University of Washington.
https://covid19.healthdata.org/canada?view=total-deaths&tab=trendView the latest modeling from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.

Johns Hopkins University of Medicine Coronavirus Resource Centre
https://coronavirus.jhu.edu/map.html

New York City Covid Data (approximately 8.34 million people)
https://github.com/nychealth/coronavirus-data/tree/master/totals#deaths-by-underlying-conditioncsvFirefox does not display graph data properly.  As of Feb 2 2021: deaths with known comorbidities 84.31%; deaths with NO known comorbidities = 0.56%; deaths with known and possible comorbidities = 99.43%. Underlying comorbidities currently include diabetes, lung disease, cancer, immunodeficiency, heart disease, hypertension, asthma, kidney disease, gastrointestinal/liver disease, and obesity.

OurWorldinData
Daily updates on COVID-19 data.
https://ourworldindata.org/coronavirus

UK Office for National Statistics
For deaths involving Covid-19, the average number of pre-existing conditions was more than 2, between March and June 2020 in England and Wales.
https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/bulletins/deathsinvolvingcovid19englandandwales/deathsoccurringinjune2020#pre-existing-conditions-of-people-who-died-with-covid-19

World Health Covid Dashboard
https://covid19.who.int/

Worldometer Coronavirus Info
https://www.worldometers.info/coronavirus/coronavirus-age-sex-demographics/