Swab antigen dan rapid antigen: Clouds and Doubts of "COVID-19 Sequelae" - part 2Note that although this paper was published in August 2021, it actually studied cases before January 1, 2021.

Biocredit swab antigen: New Zealand will adjust epidemic prevention measures According to statistics from Johns Hopkins University in the United States, as of 14:15 on the 21st, Beijing time, there were 470,740,762 confirmed cases and 6,077,597 deaths worldwide.