AUTHOR=Bitzegeio Julia , Hemmers Lukas , Bartel Alexander , Werber Dirk TITLE=Timely Monitoring COVID-19 Vaccine Protection, Berlin, Germany, April 15th to December 15th, 2021 JOURNAL=International Journal of Public Health VOLUME=67 YEAR=2022 URL=https://www.ssph-journal.org/journals/international-journal-of-public-health/articles/10.3389/ijph.2022.1604633 DOI=10.3389/ijph.2022.1604633 ISSN=1661-8564