也是CDC网站上的。注意图中的红线(代表无症状感染者)的水平几乎不随时间流逝而减低。
https://wwwnc.cdc.gov/eid/article/27/1/20-3515_article
In this study, the initial neutralizing antibody reaction appeared to correlate with the severity of the disease. However, patients with pneumonia were considerably older than asymptomatic persons, and increasing age is associated with a stronger neutralizing antibody response (10). In this study, neutralizing antibody titer decreased more in symptomatic than asymptomatic patients.