Abstract SARS-CoV-2 virus is responsible for the current COVID-19 pandemic, which has resulted in more than 2 million confirmed cases and 139,515 deaths in 213 countries, areas and territories as of 20th April 2020. Although reverse transcription polymerase chain reaction is the diagnostic test, screening studies for SARS-CoV-2 antibodies are essential for our extensive knowledge of the viral spread, formation of collective immunity, prophylaxis and treatment algorithms for the infection. We investigated 586 outpatients, for IgM and IgG antibodies, by their request in Varna and the region of northeastern Bulgaria. All of them were patients of medical diagnostic laboratory “STATUS”, Varna city. We used serological, immunochromatographic tests (rapid tests) at least seven days after suspected viral infection. Twenty-eight of the serum samples were SARS-CoV-2 Ab positive: 4.8% (95% CI: 3.2–6.9%, n = 28). IgM Ab only were detected in 1.0% (95% CI: 0.4–2.2%, n = 6), IgG Ab only in 1.2% (95% CI: 0.5–2.5%, n = 7) and both IgM/IgG Ab in 2.6% (95% CI: 1.5–4.2%, n = 15), from all of the tested individuals (n = 586). In order to understand how many people have contracted the virus, to strengthen our collective immunity and to be able to assess the risk, in the aftermath, it is essential to investigate (IgM/IgG) antibody titers.

中文翻译：

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SARS-CoV-2：保加利亚东北部的血清流行病学模式

摘要 SARS-CoV-2 病毒是当前 COVID-19 大流行的罪魁祸首，截至 2020 年 4 月 20 日，该病毒已在 213 个国家、地区和领土上造成超过 200 万确诊病例和 139,515 人死亡。尽管逆转录聚合酶链反应是SARS-CoV-2 抗体的诊断测试和筛查研究对于我们广泛了解病毒传播、集体免疫的形成、感染的预防和治疗算法至关重要。我们应瓦尔纳和保加利亚东北部地区的要求调查了 586 名门诊患者的 IgM 和 IgG 抗体。他们都是瓦尔纳市医学诊断实验室“STATUS”的患者。我们在疑似病毒感染后至少 7 天使用血清学、免疫层析检测（快速检测）。28 份血清样本为 SARS-CoV-2 Ab 阳性：4.8%（95% CI：3.2-6.9%，n = 28）。仅在 1.0%（95% CI：0.4-2.2%，n = 6）中检测到 IgM Ab，仅在 1.2%（95% CI：0.5-2.5%，n = 7）中检测到 IgG Ab，在2.6%（95% CI：1.5–4.2%，n = 15），来自所有测试个体（n = 586）。为了了解有多少人感染了病毒，增强我们的集体免疫力并能够评估风险，在此之后，有必要调查 (IgM/IgG) 抗体滴度。