Chitre Smit, Barrie Mohamed Bailor, Kanu Joseph Sam, Conteh Theophilus S, Bayoh Mohamed, Kamara Matilda N, Bangura Haja Fatmata, Lascher Jonathan S, Frankfurter Raphael, Goldberg Sarah A, Glidden David V, Kelly J Daniel, Lakoh Sulaiman, Richardson Eugene T
Department of Global Health and Social Medicine, Harvard Medical School, Boston, Massachusetts, United States of America.
Partners In Health, Kono, Sierra Leone.
PLOS Glob Public Health. 2025 Apr 16;5(4):e0004273. doi: 10.1371/journal.pgph.0004273. eCollection 2025.
Based on a serosurvey conducted in March 2021, Barrie and colleagues published the first nationally representative SARS-CoV-2 serosurvey in Africa, estimating a SARS-CoV-2 seroprevalence of 2.6% in Sierra Leone, 43 times higher than the reported number of cases at that time. Over the following two years, increasingly transmissible variants-specifically Delta and Omicron-proliferated across the globe, and their impact in Africa is poorly understood. Additional nationally representative seroprevalence data are therefore necessary to understand the pandemic's progression on the continent and for evaluating containment measures and future preparedness. Our follow-up nationally representative survey was conducted in Sierra Leone from February to March 2023. We returned to the 120 Enumeration Areas throughout the country collecting blood samples from one or more individuals per household as well as information on sociodemographic characteristics, history of COVID-19 infection and immunization, and attitudes towards vaccination. The weighted overall seroprevalence (vaccinated and/or SARS-CoV-2 infection) for individuals >19 years of age was 33% (95% CI 29-37). Using the data and distributions from our previous serosurvey, the weighted predicted seroprevalence (any prior SARS-CoV-2 infection) for the general population was 28% (95% CI 15-41). The weighted predicted seroprevalence was ~11 times higher than the pre-Delta/Omicron prevalence. It was also over 300 times higher than the reported number of cases. Despite this, overall seroprevalence was low compared with countries in Europe and the Americas (pointing towards lower transmission in Sierra Leone). In addition, our results suggest the following regarding prevention campaigns claiming to have vaccinated 70% of adults in Sierra Leone as of December 2022: 1) they resulted in limited seroconversion; 2) there was significant waning of immunity; and/or 3) many less individuals were vaccinated than reported. Regardless of the cause, the utility of COVID-19 Vaccine Delivery Partnership (CoVDP) efforts three years into the pandemic is called into question.
基于2021年3月进行的一项血清学调查，巴里及其同事发表了非洲首个具有全国代表性的新冠病毒血清学调查报告，估计塞拉利昂的新冠病毒血清阳性率为2.6%，是当时报告病例数的43倍。在接下来的两年里，传播性越来越强的变异毒株——特别是德尔塔毒株和奥密克戎毒株——在全球范围内扩散，而它们对非洲的影响却知之甚少。因此，需要更多具有全国代表性的血清阳性率数据，以了解该流行病在非洲大陆的发展情况，并评估防控措施及未来的应对准备。我们于2023年2月至3月在塞拉利昂开展了后续的全国代表性调查。我们重返全国120个普查区，从每户抽取一人或多人采集血样，并收集社会人口学特征、新冠病毒感染史和免疫情况，以及对疫苗接种的态度等信息。19岁以上人群的加权总体血清阳性率（接种疫苗和/或感染新冠病毒）为33%（95%置信区间29 - 37）。利用我们之前血清学调查的数据和分布情况，普通人群的加权预测血清阳性率（既往曾感染过新冠病毒）为28%（95%置信区间15 - 41）。加权预测血清阳性率比德尔塔/奥密克戎毒株出现之前的流行率高出约11倍，也比报告的病例数高出300多倍。尽管如此，与欧洲和美洲国家相比，塞拉利昂的总体血清阳性率较低（这表明塞拉利昂的传播率较低）。此外，关于截至2022年12月声称已为70%的塞拉利昂成年人接种疫苗的预防运动，我们的结果表明：1）这些运动导致的血清转化有限；2）免疫力出现了显著下降；和/或3）实际接种疫苗的人数比报告的要少得多。无论原因是什么，新冠疫苗交付伙伴关系（CoVDP）在疫情爆发三年后的成效都受到了质疑。
