Serosurveillance of SARS-CoV-2 among the Healthcare Workers of a Tertiary Care Teaching Institution during the Post Lockdown Phase in Central Kerala, India
Authors: Rafi Aboobacker Mohamed , Tomy Manglin Monica Lisa Joseph , Thomas Ronnie , Valsan Chithra , Unnikrishnan UG , Innah Susheela J , Kuttichira Praveenlal 
Published: October 2021

Introduction: The hallmark of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is high infectivity, pre symptomatic transmission and asymptomatic prevalence which could result in high cumulative numbers of infections, hospitalisations, and deaths. Kerala was the first state to confirm community transmission in July 2020. Healthcare Workers (HCWs) being in the forefront in the war against Coronavirus Disease-2019 (COVID-19) are more prone to acquire the infection and could possibly be asymptomatic sources for cluster formation. Knowing the development of immunity as shown by the presence of anti COV-2 antibodies in the population contributes to the epidemiological understanding of the disease. Aim: To determine the pattern of seropositivity of SARS-CoV-2 among the HCWs at Jubilee Mission Medical College and Research Institute, Thrissur, Kerala, India, six months after revoking the lockdown. Materials and Methods: This cross-sectional study was carried out among 423 HCWs of the medical college from September 5th to December 15th, 2020. Multistage sampling was done with the hospital block as the first stage and departments as the second stage. Blood sample was collected and Anti SARS COV-2 IgG antibody testing which targets the Spike Protein 1 (SP1) was done using the vitros chemiluminescence platform (Orthoclinical diagnostics, USA). For the summary of demographic characteristics, continuous variables were summarised as mean values and Standard Deviation (SD) while categorical variables were summarised as proportions. The χ2 test was used for comparing the epidemiological features between positive and negative cases. Chi-square test for trend analysis was done for exploring the relationship of the degree of severity with test positivity. All analyses were conducted using Statistical Package for the Social Sciences (SPSS) version 25.0. Results: Jubilee Mission Medical College had 2785 working staff at the time of study. A total of 423 staff consented and their samples were tested. Thirty seven staff members tested positive for COVID-19 antibody, yielding an overall prevalence of 8.75% (95% CI, 6.23-11.86). A 86.5% (32/37) of them were having a history of COVID-19 Antigen/Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) Positivity. A statistically significant linear trend (p-value=0.00001) was observed, between seropositivity and the degree of severity of COVID-19. Among the various factors which increase the risk of seroconversion, history of undergoing quarantine (p-value <0.001), contact with a confirmed case (p-value=0.002), contact with a caregiver for COVID-19 (p-value=0.001) and history of upper respiratory symptoms (p-value=0.001), were found to be significantly associated with positive serology. Conclusion: The pattern of seropositivity across the different category of HCWs observed in the present study showed a higher prevalence among nurses. Being an educational institution, it was obligatory to train all the elements of care delivery to the future generation of HCWs. Acquiring experience from a small but relevant sample was expected to facilitate larger community study envisaged in peripheral areas Jubilee Mission Hospital served.