Department of Microbiology, HIMSR & HAHC Hospital, New Delhi, 110062, India.
Department of Biochemistry, HIMSR & HAHC Hospital, New Delhi, 110062, India.
Indian J Med Microbiol. 2022 Apr-Jun;40(2):279-284. doi: 10.1016/j.ijmmb.2021.12.012. Epub 2021 Dec 31.
Identifying asymptomatic SARS-COV-2 carriage is one of the crucial factors in controlling the COVID 19 pandemic. The relationship between the asymptomatic viral carriage and the rate of seroconversion needs better understanding. The present study was conducted to identify the asymptomatic COVID-19 infection and seropositivity in high-risk contacts in the southern district of Delhi, India.
Following the screening of 6961 subjects, a total of 407 asymptomatic high-risk subjects were selected. Demographic data, socioeconomic status, and history of COVID-19 related symptoms in the last 4 months were recorded. Blood samples and Nasopharyngeal/oropharyngeal swabs were collected for the detection of SARS-COV-2 RNA and anti-SARS-COV-2 antibodies.
55 asymptomatic high-risk subjects (13.5%) tested positive for SARS-COV-2 infection and among them, 70.9% remained asymptomatic throughout their course of infection. The seropositivity among the subjects was 28.9% (n = 118) and was found significantly higher among lower-middle socioeconomic strata (p = 0.01). The antibody levels were significantly higher (p = 0.033) in individuals with a previous history of COVID-19 like symptoms as compared to the subjects, who had no such history. Asymptomatic healthcare workers showed a significantly increased rate of SARS-COV-2 infection (p = 0.004) and seropositivity (p = 0.005) as compared to the non-healthcare workers. Subjects, who were exposed to infection at their workplace (non-hospital setting) had the least RT-PCR positivity rate (p = 0.03).
A large proportion of SARS-COV-2 infection remains completely asymptomatic. The rate of asymptomatic carriage and seropositivity is significantly higher in healthcare workers as compared to the general population. The level of SARS-COV-2 antibodies is directly related to the appearance of symptoms. These observations may contribute to redefining COVID 19 screening, infection control, and professional health practice strategies.
识别无症状 SARS-CoV-2 携带是控制 COVID-19 大流行的关键因素之一。无症状病毒携带与血清转化率之间的关系需要更好地理解。本研究旨在确定印度德里南部地区高危接触者中的无症状 COVID-19 感染和血清阳性率。
在对 6961 名受试者进行筛查后，共选择了 407 名无症状高危受试者。记录了人口统计学数据、社会经济地位以及过去 4 个月内与 COVID-19 相关的症状史。采集血液样本和鼻咽/口咽拭子，用于检测 SARS-CoV-2 RNA 和抗 SARS-CoV-2 抗体。
55 名无症状高危受试者（13.5%）检测出 SARS-CoV-2 感染呈阳性，其中 70.9%在整个感染过程中保持无症状。受试者的血清阳性率为 28.9%（n=118），中低收入社会阶层的血清阳性率明显更高（p=0.01）。与无此类病史的受试者相比，有 COVID-19 样症状既往史的个体的抗体水平显著更高（p=0.033）。与非医护人员相比，无症状医护人员的 SARS-CoV-2 感染率（p=0.004）和血清阳性率（p=0.005）显著增加。与在非医院环境（工作场所）接触感染的受试者相比，工作场所（非医院环境）接触感染的受试者的 RT-PCR 阳性率最低（p=0.03）。
很大一部分 SARS-CoV-2 感染完全无症状。与一般人群相比，医护人员无症状携带和血清阳性率显著更高。SARS-CoV-2 抗体水平与症状出现直接相关。这些观察结果可能有助于重新定义 COVID-19 筛查、感染控制和专业卫生实践策略。
