Frontiers in Public Health (Apr 2022)

Previous SARS-CoV-2 Infection Status Among the Current RT-PCR-Positive Individuals Affected During the Second Wave of COVID-19 Infections in Chennai, India

  • Jeromie Wesley Vivian Thangaraj,
  • Muthusamy Santhosh Kumar,
  • C. P. Girish Kumar,
  • Pragya Yadav,
  • D. Sudha Rani,
  • T. Karunakaran,
  • Manoj Murhekar

DOI
https://doi.org/10.3389/fpubh.2022.836454
Journal volume & issue
Vol. 10

Abstract

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India witnessed a very strong second wave of coronavirus disease 2019 (COVID-19) during March and June 2021. Newly emerging variants of concern can escape immunity and cause reinfection. We tested newly diagnosed COVID-19 cases during the second wave in Chennai, India for the presence of Immunoglobulin G (IgG) antibodies to estimate the extent of re-infection. Of the 902 unvaccinated COVID-19 positive individuals, 53 (26.5%) were reactive for IgG antibodies and non-reactive for Immunogobulin M (IgM) antibodies. Among the 53 IgG-positive individuals, the interval between symptom onset (or last contact with the known case in case of asymptomatic) was <5 days in 29 individuals, ≥5 days in 11 individuals, while 13 asymptomatic individuals did not know their last contact with a positive case. The possible re-infections ranged between 3.2% (95% CI: 2.2–4.5%) and 4.3% (95% CI: 3.4–6.2%). The findings indicate that re-infection was not a major reason of the surge in cases during second wave. The IgG seropositivity among recently diagnosed unvaccinated COVID-19 patients could provide early indications about the extent of re-infections in the area.

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