SARS-CoV-2 antibody prevalence in a pediatric cohort of unvaccinated children in Mérida, Yucatán, México

The prevalence of SARS-CoV-2 exposure in children during the global Covid-19 pandemic has been underestimated due to lack of testing and the relatively mild symptoms in adolescents. Understanding the exposure rates in the pediatric population is essential as children are the last to receive vaccines and can act as a source for SARS-CoV-2 mutants that may threaten vaccine escape. This cross-sectional study aims to quantify the prevalence of anti-SARS-CoV-2 serum antibodies in children in a major city in Mexico in the Spring of 2021 and determine if there are any demographic or socioeconomic correlating factors. We obtained socioeconomic information and blood samples from 1,005 children from 50 neighborhood clusters in Merida, Yucatan, Mexico. We then tested the sera of these participants for anti-SARS-CoV-2 IgG and IgM antibodies using lateral flow immunochromatography. We found that 25.5% of children in our cohort were positive for anti-SARS-CoV-2 antibodies and there was no correlation between age and antibody prevalence. Children that lived with large families were statistically more likely to have antibodies against SARS-CoV-2. Spatial analyses identified two hotspots of high SARS-CoV-2 seroprevalence in the west of the city. These results indicate that a large urban population of unvaccinated children has been exposed to SARS-CoV-2 and that a major correlating factor was the number of people within the child’s household with a minor correlation with particular geographical hotspots. There is also a larger population of children that may be susceptible to future infection upon easing of social distancing measures. These findings suggest that in future pandemic scenarios, limited public health resources can be best utilized on children living in large households in urban areas全球新型冠状病毒肺炎（COVID-19）大流行期间，由于检测资源匮乏以及青少年感染者症状相对轻微，儿童群体中严重急性呼吸综合征冠状病毒2型（SARS-CoV-2）暴露率曾被低估。明确儿童群体的病毒暴露率至关重要：儿童是最晚接种疫苗的人群，且可能成为引发疫苗逃逸的SARS-CoV-2变异株的传播源头。本项横断面研究旨在量化2021年春季墨西哥某大城市儿童体内抗SARS-CoV-2血清抗体的阳性率，并探究是否存在相关人口学或社会经济学影响因素。我们从墨西哥尤卡坦州梅里达市的50个社区集群中招募了1005名儿童，收集其社会经济学信息与血液样本。随后采用侧向流免疫层析法，对所有受试者的血清样本开展抗SARS-CoV-2免疫球蛋白G（IgG）与免疫球蛋白M（IgM）抗体检测。研究结果显示，本队列中25.5%的儿童抗SARS-CoV-2抗体检测呈阳性，且儿童年龄与抗体阳性率无显著相关性。从统计学角度来看，与大家庭共同居住的儿童感染SARS-CoV-2并产生抗体的概率更高。空间分析结果显示，该市西部存在两处SARS-CoV-2血清阳性率较高的聚集热点区域。上述结果表明，该城市大量未接种疫苗的儿童曾暴露于SARS-CoV-2，其中最主要的相关影响因素为儿童家庭居住人数，而特定地理热点区域仅存在较弱相关性。此外，随着社交距离管控措施的放宽，仍有大量儿童群体存在未来感染SARS-CoV-2的风险。本研究结果提示，在未来的大流行应对中，公共卫生有限资源应优先投向城市地区的大家庭居住儿童群体。