Abstract
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.
Keywords: COVID-19; IgG antibody; SARS-CoV-2; genomic sequencing; reinfection.
【저자키워드】 COVID-19, SARS-CoV-2, Reinfection, IgG antibody, genomic sequencing, 【초록키워드】 coronavirus disease, antibodies, IgG, IgM, Coronavirus disease 2019, Immunity, antibody, India, variants of concern, Reinfection, Immunoglobulin G, IgG antibody, Asymptomatic, Immunoglobulin, IgG antibodies, Re-infection, Seropositivity, second wave, genomic, genomic sequencing, Contact, COVID-19 patient, Chennai, Re-infections, contact with, symptom onset, 95% CI, COVID-19 case, indication, positive, positive individuals, asymptomatic individual, reactive, tested, diagnosed, individuals, ranged, 【제목키워드】 Wave, status, individual, second, current,