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2. Centers for Disease Control and Prevention. CDC recommends additional boosters for certain individuals. 29 Mar 2022. https://www.cdc.gov/media/releases/2022/s0328-covid-19-boosters.html
3. Centers for Disease Control and Prevention. Covid Data Tracker: Monitoring variant proportions. 26 Mar 2022. https://covid.cdc.gov/covid-data-tracker/#variant-proportions
4. Kimball S. Top FDA official says fully vaccinated Americans may need more covid shots this fall. CNBC. 29 Mar 2022. https://www.cnbc.com/2022/03/29/top-fda-official-says-fully-vaccinated-americans-may-need-more-covid-shots-this-fall.html
5. Waning 2-Dose and 3-Dose Effectiveness of mRNA Vaccines Against COVID-19–Associated Emergency Department and Urgent Care Encounters and Hospitalizations Among Adults During Periods of Delta and Omicron Variant Predominance — VISION Network, 10 States, August 2021–January 2022