Does heterogeneity define COVID-19 transmission – sero-epidemiological survey data from a Central Indian urban settlement

Relaxation of mass quarantine (lockdown) measures has led to an increase in the daily positivity rate of SARS-CoV-2. However, the pattern and dynamics of its spread has been heterogenous across and within the states of India. This sero-epidemiological prevalence survey conducted in the city of Ujjain is one of the earliest such studies conducted to understand the determinants and dynamics of spread of COVID-19 in Ujjain and similar cities of Madhya Pradesh.
A total of 4,883 individuals chosen through a stratified multi-stage random sampling method, were approached to capture socio-demographic information and any history of symptoms associated with COVID-19. A sample of venous blood was also collected and assessed for the presence of SARS-CoV-2 specific antibodies using the Electrochemiluminescence Immunoassay (ECLIA) technique.
Overall unadjusted sero-prevalence for anti-SARS-CoV-2 antibody was found to be 14.2% (95% CI: 13.2% - 15.2%), and adjusted sero-prevalence was found to be 13.9% (95% CI: 10.4% - 18%). The adjusted sero-prevalence was highest in the age-group between 30 and 45 years (17.1%) and was lowest in children <15 years (9.5%). Sero-positivity was significantly higher in males (p=0.006) and in the 30-45 years age group (p=0.009). Adjusted titre values for anti-SARS-CoV-2 antibody were found to be 10.4 COI (SE = 3.38 COI) for the High Burden tertile; 4.8 (SE = 1.34 COI) for the Intermediate Burden tertile; and 6.1 COI (SE = 2.19 COI) for the Low Burden tertile.

大规模防疫封控措施的放宽导致了严重急性呼吸综合征冠状病毒2（SARS-CoV-2）日阳性率上升，但该病毒在印度各邦及邦内的传播模式与动力学特征存在显著异质性。本次在乌贾因市开展的血清流行病学现况调查（sero-epidemiological prevalence survey），是探究乌贾因及中央邦（Madhya Pradesh）同类城市新型冠状病毒肺炎（COVID-19）传播决定因素与动力学特征的首批同类研究之一。
本研究采用分层多阶段随机抽样方法，共招募4883名受试者，收集其社会人口学信息及新冠病毒感染相关症状史；同时采集静脉血样，采用电化学发光免疫分析法（Electrochemiluminescence Immunoassay, ECLIA）检测样本中新冠病毒特异性抗体。
抗新冠病毒抗体的总体未校正血清阳性率为14.2%（95%置信区间：13.2%~15.2%），校正后血清阳性率为13.9%（95%置信区间：10.4%~18%）。校正后血清阳性率在30~45岁年龄组最高（17.1%），在15岁以下儿童组最低（9.5%）。男性（p=0.006）及30~45岁年龄组的血清阳性率显著更高。抗新冠病毒抗体的校正滴度值显示：高负担三分位组为10.4 COI（标准误SE=3.38 COI），中负担三分位组为4.8（SE=1.34 COI），低负担三分位组为6.1 COI（SE=2.19 COI）。