1. World Health Organization Coronavirus Dashboard https://covid19.who.int/
2. Centers for Disease Control and Prevention Covid Data Tracker, https://covid.cdc.gov/COVID-data-tracker/#trends_weekleycases_select_00
3. Post COVID-19 Condition (Long COVID);World Health Organization,2022
4. Challenges in defining long COVID: striking differences across literature, electronic health records, and patient-reported information;H.M. Rando;medRxiv,2021
5. US Census Household Pulse Survey https://www.census.gov/programs-surveys/household-pulse-survey/data.html