Kumar Narendra, Shahul Hameed Shafeeq K, Babu Giridhara R, Venkataswamy Manjunatha M, Dinesh Prameela, Kumar Bg Prakash, John Daisy A, Desai Anita, Ravi Vasanthapuram
Department of Neurovirology, National Institute of Mental Health And Neuro Sciences (NIMHANS), Hosur Road, Bengaluru 560029, India.
Indian Institute of Public Health, Public Health Foundation of India, Bengaluru, India.
EClinicalMedicine. 2021 Feb;32:100717. doi: 10.1016/j.eclinm.2020.100717. Epub 2021 Jan 6.
The huge surge in COVID-19 cases in Karnataka state, India, during early phase of the pandemic especially following return of residents from other states and countries required investigation with respect to transmission dynamics, clinical status, demographics, comorbidities and mortality. Knowledge on the role of symptomatic and asymptomatic cases in transmission of SARS-CoV-2 was not available.
The study included all the cases reported from March 8 - May 31, 2020. Individuals with a history of international or domestic travel from high burden states, Influenza-like Illness or Severe Acute Respiratory Illness and high-risk contacts of COVID-19 cases were included. Detailed analysis based on contact tracing data available from the line-list of state surveillance unit was performed using cluster network analysis software.
Amongst the 3404 COVID-19 positive cases, 3096 (91%) were asymptomatic while 308 (9%) were symptomatic. Majority of asymptomatic cases were in the age range of 16 and 45 years while symptomatic cases were between 31 and 65 years. Mortality rate was especially higher among middle-aged and elderly cases with co-morbidities, 34/38 (89·4%). Cluster network analysis of 822 cases indicated that the secondary attack rate, size of the cluster and superspreading events were higher when the source case was symptomatic as compared to an asymptomatic.
Our findings indicate that both asymptomatic and symptomatic SARS-CoV-2 cases transmit the infection, although symptomatic cases were the main driving force within the state during the beginning of the pandemic. Considering the large proportion of asymptomatic cases, their ability to spread infection cannot be overlooked. Notwithstanding the limitations and bias in identifying asymptomatic cases, the findings have major implications for testing policies. Active search, early testing and treatment of symptomatic elderly patients with comorbidities should be prioritized for containing the spread of COVID-19 and reducing mortality.
Intermediate Fellowship, Wellcome Trust-DBT India Alliance to Giridhara R Babu, Grant number: IA/CPHI/14/1/501499.
在疫情早期，印度卡纳塔克邦新冠肺炎病例激增，尤其是在居民从其他邦和国家返回之后，这就需要对传播动态、临床状况、人口统计学、合并症和死亡率进行调查。当时尚不清楚有症状和无症状病例在严重急性呼吸综合征冠状病毒2（SARS-CoV-2）传播中的作用。
该研究纳入了2020年3月8日至5月31日报告的所有病例。纳入有来自高负担邦的国际或国内旅行史、流感样疾病或严重急性呼吸综合征以及新冠肺炎病例的高风险接触者。使用聚类网络分析软件，基于从邦监测单位的一览表中获得的接触者追踪数据进行详细分析。
在3404例新冠肺炎阳性病例中，3096例（91%）为无症状感染者，308例（9%）为有症状感染者。大多数无症状病例年龄在16至45岁之间，而有症状病例年龄在31至65岁之间。合并症的中年和老年病例死亡率尤其较高，为34/38（89.4%）。对822例病例的聚类网络分析表明，与无症状传染源相比，有症状传染源的二代发病率、聚集规模和超级传播事件更高。
我们的研究结果表明，无症状和有症状的SARS-CoV-2病例均可传播感染，尽管在疫情初期有症状病例是该邦内的主要传播驱动力。鉴于无症状病例占很大比例，其传播感染的能力不容忽视。尽管在识别无症状病例方面存在局限性和偏差，但这些发现对检测政策具有重要意义。为控制新冠肺炎传播和降低死亡率，应优先对有合并症的有症状老年患者进行主动搜索、早期检测和治疗。
惠康信托基金会-印度生物技术部联盟授予吉里达拉·R·巴布的中级奖学金，资助编号：IA/CPHI/14/1/501499。
