We collected 314 serum samples from 97 patients with COVID-19. Antibody responses were tested using an indirect immunofluorescence assay (IFA), enzyme-linked immunosorbent assay (ELISA), and plaque reduction neutralization test (PRNT) to detect specific neutralizing antibodies.
The positivity rates for neutralizing antibodies at a 1:10 titer cutoff were 58.1% at 1 week, 97.8% at 4 weeks, and 78% at 1 year after symptom onset (53.8% in asymptomatic patients and 89.3% in symptomatic patients). The IFA and anti-S1 ELISA IgG results significantly correlated with neutralizing antibody titers. Critical/fatal cases showed significantly higher antibody titers than the asymptomatic or mild-to-moderate illness groups. Nonetheless, the median number of days to the seroconversion of neutralizing antibodies was 10 and 15 in asymptomatic and symptomatic patients, respectively. The asymptomatic group had a significantly higher neutralizing potency index than the mild-to-severe illness groups.
Neutralizing antibodies corresponded to earlier seroconversion but had a shorter presence in the asymptomatic group than in the symptomatic group and were still present 1 year after symptom onset in critical/fatal cases.
我们收集了97例COVID-19患者的314份血清样本。使用间接免疫荧光测定(IFA)测试抗体反应,酶联免疫吸附测定(ELISA),和斑块减少中和试验(PRNT)检测特异性中和抗体。
在1:10滴度截止时,中和抗体的阳性率在1周时为58.1%,4周时97.8%,症状发作后1年为78%(无症状患者为53.8%,有症状患者为89.3%)。IFA和抗S1ELISAIgG结果与中和抗体滴度显著相关。危重/致命病例的抗体滴度明显高于无症状或轻度至中度疾病组。尽管如此,在无症状和有症状的患者中,中和抗体血清转换的中位天数为10和15,分别。无症状组的中和效能指数明显高于轻度至重度疾病组。
中和抗体对应于较早的血清转换,但在无症状组比有症状组短,在严重/致命病例中症状发作后1年仍存在。