Paixao Joana, Galangue Maria, Gaston Celestina, Carralero Raísa, Lino Celestina, Júlio Gracieth, David Zinga, Francisco Moises, Sebastião Cruz S, Sacomboio Euclides N M, Morais Joana, Francisco Ngiambudulu M
Grupo de Investigação Microbiana e Imunológica, Instituto Nacional de Investigação em Saúde (National Institute for Health Research), Luanda, Angola.
Unidade de Ensino e Investigação de Microbiologia Médica, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisboa, Portugal.
Infect Drug Resist. 2022 Feb 19;15:533-544. doi: 10.2147/IDR.S344437. eCollection 2022.
The global emergence of coronavirus disease 2019 (COVID-19) has challenged healthcare and rapidly spread over the globe. Early detection of new infections is crucial in the control of emerging diseases. Evidence of early recorded COVID-19 cases outside China has been documented in various countries. In this study, we aimed to identify the time of SARS-CoV-2 infection circulation by retrospectively analyzing sera of measles patients, weeks before the reported first COVID-19 cases in Angola.
We examined the humoral response against SARS-CoV-2 by using an enzyme-linked immunosorbent assay (ELISA)-based assay on a combined two-step sandwich enzyme immunoassay method. In total, we received 568 study patients with blood specimens collected from 23 September 2019 to 28 February 2020, 442 sera samples that met the criteria of the study were withdrawn and selected from the overall 568 received samples. In this study, we considered seropositives, patients who tested positive for SARS-CoV-2 immunoglobulin G (IgG) and M (IgM) antibodies with the index value >1.
Of the 442 sera samples that met the criteria of the study, 204 were measles seropositive. Forty out of 204 were confirmed reactive to SARS-CoV-2 viral proteins using IgG and IgM more than 2 weeks before the first reported case in Angola. The humoral response analysis showed significant differences ( = 0.01) between the IgG and IgM indexes in the unvaccinated measles patients. Similarly, a significant difference ( = 0.001) was seen between the IgG and IgM indexes in the vaccinated measles patients.
Here, using the humoral response analysis, we report the identification of early circulation SARS-CoV-2 infection weeks before the first recognized cases in the Republic of Angola.
2019冠状病毒病（COVID-19）在全球出现，给医疗保健带来了挑战，并在全球迅速传播。新感染的早期检测对于控制新发疾病至关重要。中国以外早期记录的COVID-19病例的证据已在各国得到记录。在本研究中，我们旨在通过回顾性分析安哥拉报告首例COVID-19病例前数周麻疹患者的血清，确定严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的传播时间。
我们采用基于酶联免疫吸附测定（ELISA）的两步夹心酶免疫测定法，检测针对SARS-CoV-2的体液免疫反应。我们共接收了568例研究患者，其血液标本采集于2019年9月23日至2020年2月28日，从总共568份接收样本中提取并选取了442份符合研究标准的血清样本。在本研究中，我们将严重急性呼吸综合征冠状病毒2免疫球蛋白G（IgG）和M（IgM）抗体检测指数值>1的血清反应阳性患者视为血清阳性。
在442份符合研究标准的血清样本中，204份为麻疹血清阳性。在安哥拉报告首例病例前2周多，204份样本中有40份通过IgG和IgM检测证实对SARS-CoV-2病毒蛋白呈反应性。体液免疫反应分析显示，未接种麻疹疫苗患者的IgG和IgM指数之间存在显著差异（P=0.01）。同样，接种麻疹疫苗患者的IgG和IgM指数之间也存在显著差异（P=0.001）。
在此，通过体液免疫反应分析，我们报告了在安哥拉共和国首例确诊病例前数周就已发现SARS-CoV-2感染的早期传播情况。
