ICMR-National Institute of Epidemiology, Chennai, India.
ICMR-National Institute of Virology, Pune, India.
Front Public Health. 2022 Apr 4;10:836454. doi: 10.3389/fpubh.2022.836454. eCollection 2022.
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.
印度在 2021 年 3 月至 6 月期间经历了非常强烈的 2019 年冠状病毒病（COVID-19）第二波疫情。新出现的关注变种可以逃避免疫并导致再次感染。我们在印度钦奈对第二波疫情中的新诊断 COVID-19 病例进行了 IgG 抗体检测，以评估再感染的程度。在 902 名未接种疫苗的 COVID-19 阳性个体中，有 53 名（26.5%）对 IgG 抗体呈反应性，而对免疫球蛋白 M（IgM）抗体呈非反应性。在 53 名 IgG 阳性个体中，29 名个体的症状出现（或在无症状情况下与已知病例的最后接触）之间的间隔<5 天，11 名个体的间隔≥5 天，而 13 名无症状个体不知道他们最后一次接触阳性病例。可能的再感染率在 3.2%（95%CI：2.2-4.5%）和 4.3%（95%CI：3.4-6.2%）之间。研究结果表明，再感染不是第二波疫情病例激增的主要原因。最近诊断为未接种疫苗的 COVID-19 患者中的 IgG 血清阳性率可能为该地区再感染的程度提供早期迹象。
