Abstract
We describe the epidemiological characteristics and associated risk factors of those presenting at a large testing centre for SARS-CoV-2 infection. This is a retrospective record review of individuals who underwent SARS-CoV-2 testing by reverse transcription-polymerase chain reaction (RT-PCR) at a high-throughput national-level government facility located in the north of India. Samples collected from 6 April to 31 December 2020 are included in this work and represent four highly populous regions. Additionally, there was a prospective follow-up of 1729 cases through telephone interviews from 25 May 2020 to 20 June 2020. Descriptive analysis has been performed for profiling clinic-epidemiological aspects of suspect cases. Multivariable logistic regression analysis was undertaken to determine risk factors that are associated with SARS-CoV-2 test positivity and symptom status. A total of 125 600 participants' details have been included in this report. The mean (s.d.) age of the participants was 33.1 (±15.3) years and 66% were male. Among these tested, 9515 (7.6%) were positive for COVID-19. A large proportion of positive cases were asymptomatic. In symptomatic positive cases, the commonest symptoms were cough and fever. Increasing age (groups 20-59 and ≥60 years compared to age group less than 5 years), male sex, history of international travel, symptoms for SARS-CoV-2, and participants from Delhi and Madhya Pradesh were positively associated with SARS-CoV-2 test positivity. Having co-morbidity, risk behaviours and intra-familial positivity were associated with a positive odds ratio for exhibiting SARS-CoV-2 symptoms. Intensified testing and isolation of cases, identification of both asymptomatic and symptomatic individuals and additional care of those with co-morbidities and risk behaviours will all be collectively important for disease containment in India. Reasons for differentials in testing between men and women remain an important area for in-depth study. The increased deployment of vaccines is likely to impact the trajectory of COVID-19 in the coming time, and therefore our data will serve as a comparative resource as India experiences the second wave of infection in light of newer variants that are likely to accelerate disease spread.