International Center for Diarrheal Diseases, Bangladesh, (icddr,b) Programme for Emerging Infections, Dhaka, Bangladesh.
Influenza Division, Centers for Disease Control and Prevention Regional Influenza Program, Bangkok, Thailand.
PLoS One. 2021 Aug 3;16(8):e0255646. doi: 10.1371/journal.pone.0255646. eCollection 2021.
During the 2019 novel coronavirus infectious disease (COVID-19) pandemic in 2020, limited data from several countries suggested reduced seasonal influenza viruses' circulation. This was due to community mitigation measures implemented to control the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We used sentinel surveillance data to identify changes in the 2020 influenza season compared with previous seasons in Bangladesh.
We used hospital-based influenza surveillance (HBIS) data of Bangladesh that are generated year-round and are population-representative severe acute respiratory infection (SARI) data for all age groups from seven public and two private tertiary care level hospitals data from 2016 to 2019. We applied the moving epidemic method (MEM) by using R language (v4.0.3), and MEM web applications (v2.14) on influenza-positive rates of SARI cases collected weekly to estimate an average seasonal influenza curve and establish epidemic thresholds.
The 2016-2019 average season started on epi week 18 (95% CI: 15-25) and lasted 12.5 weeks (95% CI: 12-14 weeks) until week 30.5. The 2020 influenza season started on epi week 36 and ended at epi week 41, lasting for only five weeks. Therefore, influenza epidemic started 18 weeks later, was 7.5 weeks shorter, and was less intense than the average epidemic of the four previous years. The 2020 influenza season started on the same week when COVID-19 control measures were halted, and 13 weeks after the measures were relaxed.
Our findings suggest that seasonal influenza circulation in Bangladesh was delayed and less intense in 2020 than in previous years. Community mitigation measures may have contributed to this reduction of seasonal influenza transmission. These findings contribute to a limited but growing body of evidence that influenza seasons were altered globally in 2020.
在 2020 年 2019 年新型冠状病毒传染病（COVID-19）大流行期间，来自几个国家的有限数据表明，季节性流感病毒的传播减少了。这是由于为控制严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）大流行而实施的社区缓解措施所致。我们使用哨点监测数据来确定与孟加拉国 2020 年流感季节与前几年相比的变化。
我们使用孟加拉国基于医院的流感监测（HBIS）数据，该数据全年生成，代表来自七家公立和两家私立三级保健医院的所有年龄段人群的人群代表性严重急性呼吸道感染（SARI）数据，用于 2016 年至 2019 年的 SARI 病例的流感阳性率。我们每周收集一次，每周应用 R 语言（v4.0.3）和流感阳性 SARI 病例的 MEM 网络应用程序（v2.14），以估算平均季节性流感曲线并建立流行阈值。
2016-2019 年的平均季节于 epi 周 18 日（95%CI：15-25）开始，持续 12.5 周（95%CI：12-14 周），直到 epi 周 30.5 日。2020 年的流感季节于 epi 周 36 日开始，于 epi 周 41 日结束，仅持续五周。因此，流感流行开始推迟了 18 周，缩短了 7.5 周，并且不如前四年的平均流行强度大。2020 年的流感季节与 COVID-19 控制措施停止的同一周开始，并且在措施放宽后 13 周开始。
我们的研究结果表明，2020 年孟加拉国的季节性流感传播比前几年延迟且强度降低。社区缓解措施可能促成了季节性流感传播的减少。这些发现为 2020 年全球流感季节发生变化的有限但不断增加的证据做出了贡献。
