Abstract：
OBJECTIVE: To study the dynamics of antibody responses in the real world up to 6 months following two Covishield vaccination doses and evaluate its correlation with age.
METHODS: From March 2021 to February 2022, a prospective, longitudinal study of healthcare workers (HCWs) from a dedicated COVID-19 hospital was conducted. Institutional Ethics Committee permission was obtained. HCWs were divided into two groups. The first group consisted of individuals who had received the first dose of the COVID-19 vaccine, with at least 3 weeks elapsed since the dose, and who had not received the second dose until the initial blood sample for antibody testing was obtained. The second group consisted of individuals who had received both COVID-19 doses and had at least 2 weeks between the administration of the second dose and the collection of the first sample for antibody testing. In March 2021, after undergoing phlebotomy for serum collection, the participants responded to the survey. Electrochemiluminescence immunoassay (ECLIA) was used to perform a quantitative test for antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein receptor domain [receptor binding domain (RBD)]. The test used had a 98.8% sensitivity and a 99.9% specificity. If the antibody titer was 0.80 U/mL or higher, it was deemed positive; if it was lower, it was deemed negative. Two follow-ups were conducted for both groups, 3 and 6 months following the first sample collection. During both follow-up visits, a blood sample was obtained for testing the amount of antibody response, and the history of COVID-19 disease following the initial sample was taken.
RESULTS: Every HCW had received the Covishield vaccination. After the vaccine\'s first dosage, 61 HCWs in the first group underwent antibody testing. The information about the 43 HCWs in the first group who attended the two follow-ups is as follows. There were 14 (32.6%) nurses and 5 (11.6%) doctors among the 43 HCWs. The age range was 21-55 years, with the median [interquartile range (IQR)] age being 26 (22-40) years and 20 (60.5%) being females. The vaccination series had a median (IQR) of 34 (29-49) days between doses. There was a statistically significant difference in immunoglobulin G (IgG) levels of the three samples, χ2 = 13.579, p = 0.001. Median (IQR) IgG levels of the three samples at 1 month after the first dose, 3 and 6 months after the second dose were 8511 (51-15400) U/mL, 1471 (249-5050) U/mL, and 978 (220-2854) U/mL, respectively. The antibody titer was negative for two HCWs in the first sample, positive in the rest of the samples, and positive in all samples in both follow-ups. In the second group, following two COVID-19 dosages, a total of 65 HCWs had tested positive for antibodies. The information of the 56 HCWs in group II who attended both follow-ups is as follows. Of the 56 HCWs, 15 (26.8%) were doctors, 27 (48.2%) were nurses, and 14 (25%) were others. The age range was 20-64 years, with a median (IQR) of 29.5 (22-37.7) and 31 (55.3%) female participants. The vaccination series had a median (IQR) interval of 32 (29-35) days between doses. There was a statistically significant difference in IgG levels of the three samples, χ2 = 31.107, p < 0.0001. Median (IQR) IgG levels of the three samples at 20 days, 3.8 months, and 7 months after the second dose were 2377.5, 1345.5, and 1257 U/mL, respectively. Spearman\'s rank order correlation was used to assess the association between IgG level and age in both groups. The relationship between IgG levels and age was weakly correlated and not statistically significant.
CONCLUSIONS: There is a waning of antibody titer over time postimmunization. A lower antibody titer can be a contributing factor for infections that emerge later. IgG levels postvaccination do not differ according to age.
METHODS: From March 2021 to February 2022, a prospective, longitudinal study of healthcare workers (HCWs) from a dedicated COVID-19 hospital was conducted. Institutional Ethics Committee permission was obtained. HCWs were divided into two groups. The first group consisted of individuals who had received the first dose of the COVID-19 vaccine, with at least 3 weeks elapsed since the dose, and who had not received the second dose until the initial blood sample for antibody testing was obtained. The second group consisted of individuals who had received both COVID-19 doses and had at least 2 weeks between the administration of the second dose and the collection of the first sample for antibody testing. In March 2021, after undergoing phlebotomy for serum collection, the participants responded to the survey. Electrochemiluminescence immunoassay (ECLIA) was used to perform a quantitative test for antibodies to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein receptor domain [receptor binding domain (RBD)]. The test used had a 98.8% sensitivity and a 99.9% specificity. If the antibody titer was 0.80 U/mL or higher, it was deemed positive; if it was lower, it was deemed negative. Two follow-ups were conducted for both groups, 3 and 6 months following the first sample collection. During both follow-up visits, a blood sample was obtained for testing the amount of antibody response, and the history of COVID-19 disease following the initial sample was taken.
RESULTS: Every HCW had received the Covishield vaccination. After the vaccine\'s first dosage, 61 HCWs in the first group underwent antibody testing. The information about the 43 HCWs in the first group who attended the two follow-ups is as follows. There were 14 (32.6%) nurses and 5 (11.6%) doctors among the 43 HCWs. The age range was 21-55 years, with the median [interquartile range (IQR)] age being 26 (22-40) years and 20 (60.5%) being females. The vaccination series had a median (IQR) of 34 (29-49) days between doses. There was a statistically significant difference in immunoglobulin G (IgG) levels of the three samples, χ2 = 13.579, p = 0.001. Median (IQR) IgG levels of the three samples at 1 month after the first dose, 3 and 6 months after the second dose were 8511 (51-15400) U/mL, 1471 (249-5050) U/mL, and 978 (220-2854) U/mL, respectively. The antibody titer was negative for two HCWs in the first sample, positive in the rest of the samples, and positive in all samples in both follow-ups. In the second group, following two COVID-19 dosages, a total of 65 HCWs had tested positive for antibodies. The information of the 56 HCWs in group II who attended both follow-ups is as follows. Of the 56 HCWs, 15 (26.8%) were doctors, 27 (48.2%) were nurses, and 14 (25%) were others. The age range was 20-64 years, with a median (IQR) of 29.5 (22-37.7) and 31 (55.3%) female participants. The vaccination series had a median (IQR) interval of 32 (29-35) days between doses. There was a statistically significant difference in IgG levels of the three samples, χ2 = 31.107, p < 0.0001. Median (IQR) IgG levels of the three samples at 20 days, 3.8 months, and 7 months after the second dose were 2377.5, 1345.5, and 1257 U/mL, respectively. Spearman\'s rank order correlation was used to assess the association between IgG level and age in both groups. The relationship between IgG levels and age was weakly correlated and not statistically significant.
CONCLUSIONS: There is a waning of antibody titer over time postimmunization. A lower antibody titer can be a contributing factor for infections that emerge later. IgG levels postvaccination do not differ according to age.
摘要：
目的：研究两次Covishield疫苗接种后6个月内现实世界中抗体反应的动态，并评估其与年龄的相关性。
方法：从2021年3月到2022年2月，对一家专门的COVID-19医院的医护人员(HCWs)进行了纵向研究.获得了机构伦理委员会的许可。HCWs分为两组。第一组由接受第一剂COVID-19疫苗的个体组成，自剂量以来至少已经过去了3周，并且在获得用于抗体测试的初始血液样本之前没有接受第二剂。第二组由接受过两种COVID-19剂量的个体组成，在第二次剂量给药和收集第一次样品进行抗体测试之间至少有2周的时间。2021年3月，在接受静脉切开术进行血清采集后，参与者回答了调查。电化学发光免疫分析（ECLIA）用于对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）刺突（S）蛋白受体结构域[受体结合结构域（RBD）]的抗体进行定量测试。所使用的测试具有98.8%的灵敏度和99.9%的特异性。如果抗体滴度为0.80U/mL或更高，它被认为是积极的；如果它更低，它被认为是负面的。两组均进行两次随访,在第一次样品收集后3个月和6个月。在两次后续访问中，获得血液样本用于测试抗体反应的量，并在初始样本后采集COVID-19病史。
结果：每个HCW都接受了Covishield疫苗接种。在第一次接种疫苗后，第一组中的61例HCWs接受了抗体测试。关于参加两次随访的第一组中的43名医护人员的信息如下。43名医护人员中有14名(32.6%)护士和5名(11.6%)医生。年龄范围是21-55岁,中位[四分位距（IQR）]年龄为26（22-40）岁，女性为20（60.5％）。疫苗接种系列在剂量之间具有34(29-49)天的中值(IQR)。三个样本的免疫球蛋白G(IgG)水平有统计学意义的差异,χ2=13.579,p=0.001。首次给药后1个月，三个样品的IgG水平中位数（IQR），第二次给药后3个月和6个月分别为8511（51-15400）U/mL，1471(249-5050)U/mL,和978（220-2854）U/mL，分别。第一个样本中两个HCWs的抗体滴度为阴性，其余样本呈阳性，在两次随访中，所有样本均呈阳性。在第二组中,在两次COVID-19剂量后，共有65例HCWs的抗体检测呈阳性.参加两次随访的II组中56名HCWs的信息如下。在56名HCW中，15人(26.8%)是医生，27人（48.2%）是护士，14人(25%)是其他人。年龄范围为20-64岁，中位数（IQR）为29.5（22-37.7）和31（55.3％）女性参与者。疫苗接种系列在剂量之间具有32(29-35)天的中值(IQR)间隔。三个样本的IgG水平有统计学上的显著差异,χ2=31.107,p<0.0001。三个样本在20天的IgG水平中位数(IQR),3.8个月,第二次给药后7个月分别为2377.5、1345.5和1257U/mL，分别。使用Spearman的等级顺序相关性来评估两组中IgG水平与年龄之间的关联。IgG水平与年龄之间的关系弱相关，无统计学意义。
结论：随着时间的推移，免疫后抗体滴度逐渐下降。较低的抗体滴度可能是后来出现的感染的促成因素。疫苗接种后的IgG水平不会因年龄而异。
方法：从2021年3月到2022年2月，对一家专门的COVID-19医院的医护人员(HCWs)进行了纵向研究.获得了机构伦理委员会的许可。HCWs分为两组。第一组由接受第一剂COVID-19疫苗的个体组成，自剂量以来至少已经过去了3周，并且在获得用于抗体测试的初始血液样本之前没有接受第二剂。第二组由接受过两种COVID-19剂量的个体组成，在第二次剂量给药和收集第一次样品进行抗体测试之间至少有2周的时间。2021年3月，在接受静脉切开术进行血清采集后，参与者回答了调查。电化学发光免疫分析（ECLIA）用于对严重急性呼吸综合征冠状病毒2（SARS-CoV-2）刺突（S）蛋白受体结构域[受体结合结构域（RBD）]的抗体进行定量测试。所使用的测试具有98.8%的灵敏度和99.9%的特异性。如果抗体滴度为0.80U/mL或更高，它被认为是积极的；如果它更低，它被认为是负面的。两组均进行两次随访,在第一次样品收集后3个月和6个月。在两次后续访问中，获得血液样本用于测试抗体反应的量，并在初始样本后采集COVID-19病史。
结果：每个HCW都接受了Covishield疫苗接种。在第一次接种疫苗后，第一组中的61例HCWs接受了抗体测试。关于参加两次随访的第一组中的43名医护人员的信息如下。43名医护人员中有14名(32.6%)护士和5名(11.6%)医生。年龄范围是21-55岁,中位[四分位距（IQR）]年龄为26（22-40）岁，女性为20（60.5％）。疫苗接种系列在剂量之间具有34(29-49)天的中值(IQR)。三个样本的免疫球蛋白G(IgG)水平有统计学意义的差异,χ2=13.579,p=0.001。首次给药后1个月，三个样品的IgG水平中位数（IQR），第二次给药后3个月和6个月分别为8511（51-15400）U/mL，1471(249-5050)U/mL,和978（220-2854）U/mL，分别。第一个样本中两个HCWs的抗体滴度为阴性，其余样本呈阳性，在两次随访中，所有样本均呈阳性。在第二组中,在两次COVID-19剂量后，共有65例HCWs的抗体检测呈阳性.参加两次随访的II组中56名HCWs的信息如下。在56名HCW中，15人(26.8%)是医生，27人（48.2%）是护士，14人(25%)是其他人。年龄范围为20-64岁，中位数（IQR）为29.5（22-37.7）和31（55.3％）女性参与者。疫苗接种系列在剂量之间具有32(29-35)天的中值(IQR)间隔。三个样本的IgG水平有统计学上的显著差异,χ2=31.107,p<0.0001。三个样本在20天的IgG水平中位数(IQR),3.8个月,第二次给药后7个月分别为2377.5、1345.5和1257U/mL，分别。使用Spearman的等级顺序相关性来评估两组中IgG水平与年龄之间的关联。IgG水平与年龄之间的关系弱相关，无统计学意义。
结论：随着时间的推移，免疫后抗体滴度逐渐下降。较低的抗体滴度可能是后来出现的感染的促成因素。疫苗接种后的IgG水平不会因年龄而异。
