Institute for Infectious Diseases and Endemic Diseases Control, Beijing Municipal Center for Disease Prevention and Control & Beijing Research Center for Preventive Medicine , Beijing, China.
School of Public Health and Community Medicine, The University of New South Wales , Sydney, Australia.
Hum Vaccin Immunother. 2020 Jul 2;16(7):1685-1690. doi: 10.1080/21645515.2019.1705692. Epub 2020 Jan 29.
Children aged under 5 years are particularly vulnerable to influenza infection. In this study, we aim to estimate the number and incidence of influenza among young children and estimate the impact of childhood vaccination in different scenarios from 2013/14 to 2016/17 seasons.
The number and incidence rate of influenza infections among children aged under 5 years in Beijing was estimated by scaling up observed surveillance data. Then, we used a susceptible-exposed-infected-recovery (SEIR) model to reproduce the weekly number of influenza infections estimated in Beijing during the study seasons, and to estimate the number and proportion of influenza-attributed medically attended acute respiratory infections (I-MAARI) averted by vaccination in each season. Finally, we evaluated the impact of alternative childhood vaccination programs with different coverage and speed of vaccine distribution.
The estimated average annual incidence of influenza in children aged under 5 years was 33.9% (95% confidence interval (CI): 27.5%, 47.2%) during the study period. With the actual coverage during the included seasons at around 2.9%, an average of 3.9% (95%CI: 3.5%, 4.4%) I-MAARI was reduced compared to a no-vaccination scenario. Reaching 20%, 40%, 50%, 60%, 80% and 100% vaccine coverage would lead to an overall I-MAARI reduction of 25.3%, 42.7%, 51.9%, 57.0%, 65.3% and 71.2%. At 20% coverage scenario, an average of 28.8% I-MAARI will be prevented if intensive vaccination implemented in 2 months since the vaccine released.
In Beijing, the introduction of a program for vaccinating young children, even at relatively low vaccine coverage rates, would considerably reduce I-MAARI, particularly if the vaccines can be quickly delivered.
5 岁以下儿童特别容易感染流感。本研究旨在估计 2013/14 至 2016/17 季节期间，5 岁以下儿童中流感的数量和发病率，并评估不同情景下儿童疫苗接种的影响。
通过扩大观察性监测数据，估计北京 5 岁以下儿童流感感染的数量和发病率。然后，我们使用易感-暴露-感染-恢复（SEIR）模型复制研究季节期间北京每周估计的流感感染数量，并估计每个季节疫苗接种可预防的流感相关医疗急性呼吸道感染（I-MAARI）的数量和比例。最后，我们评估了不同疫苗覆盖率和疫苗分配速度的替代儿童疫苗接种方案的影响。
研究期间，5 岁以下儿童流感的估计年平均发病率为 33.9%（95%置信区间[CI]：27.5%，47.2%）。在包括的季节中，实际覆盖率约为 2.9%，与不接种疫苗相比，平均可减少 3.9%（95%CI：3.5%，4.4%）的 I-MAARI。达到 20%、40%、50%、60%、80%和 100%的疫苗覆盖率将导致总体 I-MAARI 减少 25.3%、42.7%、51.9%、57.0%、65.3%和 71.2%。在 20%的覆盖率情景下，如果在疫苗发布后 2 个月内集中接种疫苗，平均可预防 28.8%的 I-MAARI。
在北京，即使疫苗接种率相对较低，为幼儿接种疫苗的方案也会大大降低 I-MAARI，特别是如果疫苗能够快速送达。
