Zamani Mohammad, Ghasemi Ahmad, Shamshirgaran Morteza, Ahmadpour Sajjad, Hormati Ahmad, Khodadadi Javad, Varnasseri Mehran, Amini Fatemeh, Shayanrad Amaneh, Younesi Vahid, Poustchi Hossein, Shabani Mahdi
Digestive Diseases Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran.
Healthy Ageing Research Centre, Neyshabur Faculty of Medical Sciences, Neyshabur University Medical Sciences, Neyshabur, Iran.
Avicenna J Med Biotechnol. 2022 Jul-Sep;14(3):233-238. doi: 10.18502/ajmb.v14i3.9830.
Evidence on seroconversion profile of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infected patients is limited. We mainly aimed to evaluate seroconversion and persistence of virus-specific antibodies in patients infected by coronavirus disease 2019 (COVID-19).
This prospective study was conducted on 118 patients with COVID-19 presentations admitted to three hospitals in Iran and recovered from the disease, during April and May 2020. Presence of COVID-19 was confirmed by Polymerase Chain Reaction (PCR) testing on nasopharyngeal swabs. Serum samples were collected at different time points, including 0-5, 6-15, 16-25, 26-35, and 36-95 days of clinical symptom onset. For measurement of SARS-CoV-2-specific IgG and IgM antibody titers, Iran's Food and Drug Administration-approved SARS-CoV-2 ELISA kits were used.
Serologic assay revealed that 37.3% of patients (n=44) were positive for IgM at 0-5 days interval after clinical symptom onset. This rate was 60.2% (n=71) for IgG. There were increasing IgM and IgG seroconversion rates during first 25 days of clinical symptom onset, but seropositivity started to decrease thereafter, which was more evident for IgM (17.9%) than IgG (58.9%) at the 36-95 days post symptoms appearance. In other words, it was found that 83.6% of IgM-positive and 32.9% of IgG-positive patients in the first month of clinical symptom onset became seronegative in the third month of clinical symptom onset.
The findings demonstrated that antibody responses to SARS-CoV-2 infection were developed in recovered COVID-19 patients; however, some of them were seronegative three months after onset of relevant symptoms. Furthermore, the stability of anti-SARS-CoV-2 antibodies could also correct our expectations from COVID-19 vaccination responses.
关于新型严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染患者血清转化情况的证据有限。我们的主要目的是评估2019冠状病毒病（COVID-19）感染患者中病毒特异性抗体的血清转化和持续存在情况。
这项前瞻性研究于2020年4月至5月对伊朗三家医院收治的118例有COVID-19临床表现且已康复的患者进行。通过对鼻咽拭子进行聚合酶链反应（PCR）检测确认是否存在COVID-19。在临床症状出现后的不同时间点采集血清样本，包括0 - 5天、6 - 15天、16 - 25天、26 - 35天和36 - 95天。使用伊朗食品药品监督管理局批准的SARS-CoV-2 ELISA试剂盒检测SARS-CoV-2特异性IgG和IgM抗体滴度。
血清学检测显示，临床症状出现后0 - 5天内，37.3%的患者（n = 44）IgM呈阳性。IgG的这一比例为60.2%（n = 71）。在临床症状出现的前25天内，IgM和IgG的血清转化率不断上升，但此后血清阳性率开始下降，症状出现后36 - 95天时，IgM（17.9%）比IgG（58.9%）更为明显。换句话说，发现在临床症状出现的第一个月，83.6%的IgM阳性患者和32.9%的IgG阳性患者在临床症状出现的第三个月变为血清阴性。
研究结果表明，康复的COVID-19患者对SARS-CoV-2感染产生了抗体反应；然而，其中一些患者在相关症状出现三个月后血清呈阴性。此外，抗SARS-CoV-2抗体的稳定性也可能会修正我们对COVID-19疫苗接种反应的预期。
