School of Public Health and Graduate School of Medicine, Kyoto University, Kyoto, Japan.
Front Public Health. 2022 Jun 10;10:837970. doi: 10.3389/fpubh.2022.837970. eCollection 2022.
Osaka, the third largest prefecture in Japan, experienced a rapid replacement of preexisting strains of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by variant alpha during March-April 2021. Assessing the burden of variant alpha on health centers and medical institutions is vital to anticipating the surge of patients. The present study aimed to estimate the age-dependent risks of coronavirus disease (COVID-19) putatively caused by variant alpha in Japan, focusing on epidemiological dynamics in Osaka.
Descriptive analyses were conducted using data on confirmed, severe and fatal cases of COVID-19 from 16 November 2020 to 22 May 2021. All cases were divided into 6-9 age groups to compare the risks of confirmed diagnosis, severe illness and death from COVID-19 with variant alpha to those caused by preexisting strains.
Individuals with COVID-19 aged under 30 years were more likely to be infected with variant alpha than those in their 40s. The incidence of severe illness and death among all age groups with COVID-19 due to variant alpha was higher than that due to preexisting strains. Patients older than 40 years experienced an increased risk of severe illness and death if infected with variant alpha. However, the proportion of severe cases was lower in the group aged 80 years and older infected with variant alpha than in those infected with preexisting strains.
Our analysis suggests that the incidence of infection among young people aged below 30 years old increased relative to ordinary strains. Risks of severe illness and death in patients with variant alpha COVID-19 was higher than in those with preexisting strains in Osaka, Japan. However, a decrease in the risk of severe illness was observed in people aged ≥80 years, which is probably because medical facilities in Osaka were overwhelmed in April and May 2021. Continuous monitoring of COVID-19 cases with new variants is vital to secure sufficient medical resources for all patients who require medical care.
日本第三大行政区大阪府在 2021 年 3 月至 4 月期间，迅速被变异株阿尔法取代了原有严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）的流行。评估变异株阿尔法对保健中心和医疗机构的负担对预测患者人数激增至关重要。本研究旨在估计日本由变异株阿尔法引起的冠状病毒病（COVID-19）的年龄依赖性风险，重点关注大阪的流行病学动态。
使用 2020 年 11 月 16 日至 2021 年 5 月 22 日确诊、重症和死亡 COVID-19 病例的数据进行描述性分析。所有病例分为 6-9 个年龄组，比较变异株阿尔法所致确诊、重症和死亡 COVID-19 的风险与原有流行株所致的风险。
年龄在 30 岁以下的 COVID-19 患者比 40 多岁的患者更容易感染变异株阿尔法。所有年龄组因变异株阿尔法导致的 COVID-19 重症和死亡的发生率均高于原有流行株。40 岁以上的患者感染变异株阿尔法后，重症和死亡的风险增加。然而，感染变异株阿尔法的 80 岁及以上患者的重症病例比例低于感染原有流行株的患者。
我们的分析表明，30 岁以下年轻人的感染率相对于普通株有所增加。在日本大阪，变异株阿尔法引起的 COVID-19 患者的重症和死亡风险高于原有流行株。然而，≥80 岁人群的重症风险有所降低，这可能是因为大阪的医疗设施在 2021 年 4 月和 5 月已经不堪重负。对新变异株 COVID-19 病例进行持续监测对于为所有需要医疗护理的患者确保充足的医疗资源至关重要。
