现在也就中国人干点正事了。在美国，massive infection的数据哪有人管啊。facebook当时连Covid这个单词
都不让group里艘。中国放开前后，有人专门收集数据。
“To delineate the phases of exposure, patients’ data were divided into three groups: pre-COVID (January 2021 to November 2022), mass infection (December 2022 to February 2023), and post-COVID (March 2023 to August 2024).”
Persistent attenuation of lymphocyte subsets after mass SARS-CoV-2 infection - ScienceDirect
