Department of Clinical Immunology, Zealand University Hospital, Køge, Denmark.
Department of Clinical Medicine, Copenhagen University, Copenhagen, Denmark.
Clin Infect Dis. 2021 Nov 2;73(9):e2962-e2969. doi: 10.1093/cid/ciaa1627.
Although the vast majority of individuals succumbing to infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are elderly, infection fatality rate (IFR) estimates for the age group ≥70 years are still scarce. To this end, we assessed SARS-CoV-2 seroprevalence among retired blood donors and combined it with national coronavirus disease 2019 (COVID-19) survey data to provide reliable population-based IFR estimates for this age group.
We identified 60 926 retired blood donors aged ≥70 years in the rosters of 3 regionwide Danish blood banks and invited them to fill in a questionnaire on COVID-19-related symptoms and behaviors. Among 24 861 (40.8%) responders, we invited a random sample of 3200 individuals for blood testing. Overall, 1201 (37.5%) individuals were tested for SARS-CoV-2 antibodies (Wantai) and compared with 1110 active blood donors aged 17-69 years. Seroprevalence 95% confidence intervals (CIs) were adjusted for assay sensitivity and specificity.
Among retired (aged ≥70 years) and active (aged 17-69 years) blood donors, adjusted seroprevalences were 1.4% (95% CI, .3-2.5%) and 2.5% (95% CI, 1.3-3.8%), respectively. Using available population data on COVID-19-related fatalities, IFRs for patients aged ≥70 years and for 17-69 years were estimated at 5.4% (95% CI, 2.7-6.4%) and .083% (95% CI, .054-.18%), respectively. Only 52.4% of SARS-CoV-2-seropositive retired blood donors reported having been sick since the start of the pandemic.
COVID-19 IFR in the age group >69 years is estimated to be 65 times the IFR for people aged 18-69 years.
尽管绝大多数死于严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的个体是老年人，但≥70 岁年龄组的感染病死率（IFR）估计仍很少。为此，我们评估了退休献血者中 SARS-CoV-2 的血清流行率，并将其与全国 2019 年冠状病毒病（COVID-19）调查数据相结合，为该年龄组提供可靠的基于人群的 IFR 估计。
我们在 3 家丹麦地区性血库的名册中确定了 60926 名≥70 岁的退休献血者，并邀请他们填写一份关于 COVID-19 相关症状和行为的问卷。在 24861 名（40.8%）回答者中，我们邀请了 3200 名随机样本进行血液检测。共有 1201 名（37.5%）个体接受了 SARS-CoV-2 抗体（万泰）检测，并与 1110 名年龄在 17-69 岁的活跃献血者进行了比较。血清流行率 95%置信区间（CI）根据检测灵敏度和特异性进行了调整。
在退休（年龄≥70 岁）和活跃（年龄 17-69 岁）献血者中，调整后的血清流行率分别为 1.4%（95%CI，.3-2.5%）和 2.5%（95%CI，1.3-3.8%）。使用有关 COVID-19 相关死亡的可用人口数据，估计≥70 岁患者和 17-69 岁患者的 IFR 分别为 5.4%（95%CI，2.7-6.4%）和.083%（95%CI，.054-.18%）。仅有 52.4%的 SARS-CoV-2 血清阳性退休献血者报告自大流行开始以来患病。
≥69 岁年龄组的 COVID-19 IFR 估计为 18-69 岁人群 IFR 的 65 倍。
