Background Nigeria is Africa’s most populated country. By November 2021 it had experienced three waves of SARS-CoV-2 infection. Peer-reviewed seroprevalence data assessing the proportion of the Nigerian population that have been infected were extremely limited. Methods We conducted a serosurvey in one urban site (n = 400) and one rural site (n = 402) in Kaduna State, Nigeria between 11 October 2021 and 8 November 2021. Z-tests were used to compare seroprevalence across age groups, locations and sexes. T tests were used to determine whether age or household size are associated with seropositivity. Associations between seropositivity and recent history of common Covid-19 symptoms were tested using logistic regression. Results SARS-CoV-2 antibodies were detected in 42.5% an 53.5% of participants at the urban and rural sites, respectively The overall age- and sex- stratified seroprevalence was 43.7% (42.2% for unvaccinated individuals). The data indicate an infection rate in Kaduna State ≥359-fold the rate derived from polymerase chain reaction-confirmed cases. In the urban site, seroprevalence among females and participants aged <20 was lower than other groups. Reporting loss of sense of taste and/or smell was strongly associated with seropositive status. Associations with seropositivity were also found for the reporting of dry cough, fever, headache, nausea and sore throat. Conclusions This study provides baseline SARS-CoV-2 seroprevalence in Kaduna State, Nigeria, immediately prior to the spread of the Omicron variant. It indicates that in October/November 2021, approximately 56% of the population did not have detectable antibodies, and population subgroups with particularly low seroprevalence remain. It highlights limitations in using PCR-confirmed cases to estimate infection rates. The data will inform public health strategies in Nigeria and other sub-Saharan African countries with limited SARS-CoV-2 seroprevalence data.

中文翻译：

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2021 年 10 月/2021 年 11 月，就在检测到 Omicron 变体之前，尼日利亚卡杜纳州城市和农村地区的 SARS-CoV-2 血清阳性率

背景尼日利亚是非洲人口最多的国家。到 2021 年 11 月，它已经经历了三波 SARS-CoV-2 感染。评估被感染的尼日利亚人口比例的同行评审的血清阳性率数据极为有限。方法 我们于 2021 年 10 月 11 日至 2021 年 11 月 8 日期间在尼日利亚卡杜纳州的一个城市站点 (n = 400) 和一个农村站点 (n = 402) 进行了血清调查。Z 检验用于比较不同年龄组、不同地点的血清阳性率和性别。T 检验用于确定年龄或家庭规模是否与血清阳性相关。使用逻辑回归测试血清阳性与近期常见 Covid-19 症状病史之间的关联。结果 在城市和农村地区，42.5% 和 53.5% 的参与者检测到 SARS-CoV-2 抗体，分别按年龄和性别分层的总体血清阳性率为 43.7%（未接种疫苗的个体为 42.2%）。数据表明，卡杜纳州的感染率是聚合酶链反应确诊病例感染率的 359 倍以上。在城市地区，女性和 20 岁以下参与者的血清阳性率低于其他组。报告味觉和/或嗅觉丧失与血清阳性状态密切相关。还发现干咳、发烧、头痛、恶心和喉咙痛的报告与血清阳性有关。结论 本研究提供了尼日利亚卡杜纳州在 Omicron 变体传播之前的基线 SARS-CoV-2 血清阳性率。这表明在 2021 年 10 月/11 月，大约 56% 的人口没有可检测到的抗体，血清阳性率特别低的人群亚群仍然存在。它强调了使用 PCR 确诊病例估计感染率的局限性。这些数据将为尼日利亚和其他撒哈拉以南非洲国家的公共卫生战略提供信息，这些国家的 SARS-CoV-2 血清阳性率数据有限。