Whelan Marilyn, Galipeau Yannick, White-Al Habeeb Nicole, Konforte Danijela, Abou El Hassan Mohamed, Booth Ronald A, Arnold Corey, Langlois Marc-André, Pelchat Martin
Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada.
Dynacare, Brampton, Canada.
Open Forum Infect Dis. 2023 Jul 20;10(8):ofad384. doi: 10.1093/ofid/ofad384. eCollection 2023 Aug.
SARS-CoV-2 infections have disproportionally burdened elderly populations with excessive mortality. While several contributing factors exists, questions remain about the quality and duration of humoral antibody-mediated responses resulting from infections in unvaccinated elderly individuals.
Residual serum/plasma samples were collected from individuals undergoing routine SARS-CoV-2 polymerase chain reaction testing in a community laboratory in Canada. The samples were collected in 2020, before vaccines became available. IgG, IgA, and IgM antibodies against SARS-CoV-2 nucleocapsid, trimeric spike, and its receptor-binding domain were quantified via a high-throughput chemiluminescent enzyme-linked immunosorbent assay. Neutralization efficiency was also quantified through a surrogate high-throughput protein-based neutralization assay.
This study analyzed SARS-CoV-2 antibody levels in a large cross-sectional cohort (N = 739), enriched for elderly individuals (median age, 82 years; 75% >65 years old), where 72% of samples tested positive for SARS-CoV-2 by polymerase chain reaction. The age group ≥90 years had higher levels of antibodies than that <65 years. Neutralization efficiency showed an age-dependent trend, where older persons had higher levels of neutralizing antibodies. Antibodies targeting the nucleocapsid had the fastest decline. IgG antibodies targeting the receptor-binding domain remained stable over time, potentially explaining the lack of neutralization decay observed in this cohort.
Despite older individuals having the highest levels of antibodies postinfection, they are the cohort in which antibody decay was the fastest. Until a better understanding of correlates of protection is acquired, along with the protective role of nonneutralizing antibodies, booster vaccinations remain important in this demographic.
严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染给老年人群带来了过重的死亡负担。虽然存在多种促成因素，但对于未接种疫苗的老年人感染后体液抗体介导反应的质量和持续时间仍存在疑问。
从加拿大一家社区实验室接受常规SARS-CoV-2聚合酶链反应检测的个体中收集残余血清/血浆样本。这些样本于2020年收集，当时疫苗尚未问世。通过高通量化学发光酶联免疫吸附测定法对针对SARS-CoV-2核衣壳、三聚体刺突及其受体结合域的IgG、IgA和IgM抗体进行定量。还通过基于替代高通量蛋白质的中和测定法对中和效率进行定量。
本研究分析了一个大型横断面队列（N = 739）中的SARS-CoV-2抗体水平，该队列以老年人为主（中位年龄82岁；75%年龄>65岁），其中72%的样本通过聚合酶链反应检测SARS-CoV-2呈阳性。≥90岁年龄组的抗体水平高于<65岁年龄组。中和效率呈现出年龄依赖性趋势，即老年人的中和抗体水平较高。靶向核衣壳的抗体下降最快。靶向受体结合域的IgG抗体随时间保持稳定，这可能解释了该队列中未观察到中和作用衰减的原因。
尽管老年人在感染后抗体水平最高，但他们是抗体衰减最快的人群。在更好地了解保护相关性以及非中和抗体的保护作用之前，加强疫苗接种在这一人群中仍然很重要。
