Department of Medicine, Mount Auburn Hospital, Cambridge, MA 02138, USA.
Harvard Medical School, Boston, MA 02115, USA.
J Travel Med. 2023 Sep 5;30(5). doi: 10.1093/jtm/taad102.
This review aims to summarize the transmission patterns of influenza, its seasonality in different parts of the globe, air travel- and cruise ship-related influenza infections and interventions to reduce transmission.
The seasonality of influenza varies globally, with peak periods occurring mainly between October and April in the northern hemisphere (NH) and between April and October in the southern hemisphere (SH) in temperate climate zones. However, influenza seasonality is significantly more variable in the tropics. Influenza is one of the most common travel-related, vaccine-preventable diseases and can be contracted during travel, such as during a cruise or through air travel. Additionally, travellers can come into contact with people from regions with ongoing influenza transmission. Current influenza immunization schedules in the NH and SH leave individuals susceptible during their respective spring and summer months if they travel to the other hemisphere during that time.
CONCLUSIONS/RECOMMENDATIONS: The differences in influenza seasonality between hemispheres have substantial implications for the effectiveness of influenza vaccination of travellers. Health care providers should be aware of influenza activity when patients report travel plans, and they should provide alerts and advise on prevention, diagnostic and treatment options. To mitigate the risk of travel-related influenza, interventions include antivirals for self-treatment (in combination with the use of rapid self-tests), extending the shelf life of influenza vaccines to enable immunization during the summer months for international travellers and allowing access to the influenza vaccine used in the opposite hemisphere as a travel-related vaccine. With the currently available vaccines, the most important preventive measure involves optimizing the seasonal influenza vaccination. It is also imperative that influenza is recognized as a travel-related illness among both travellers and health care professionals.
本文旨在总结流感的传播模式、其在全球不同地区的季节性、与航空旅行和游轮相关的流感感染及减少传播的干预措施。
流感在全球的季节性有所不同，在温带气候区，北半球（NH）的主要高峰期为 10 月至 4 月，南半球（SH）为 4 月至 10 月。然而，在热带地区，流感的季节性变化更为显著。流感是最常见的与旅行相关、可通过疫苗预防的疾病之一，旅行者在旅行中（如在游轮上或通过航空旅行）可能会感染流感。此外，旅行者可能会接触到来自正在发生流感传播地区的人。目前在 NH 和 SH 的流感免疫接种计划，如果旅行者在这段时间前往另一个半球，那么他们在各自的春季和夏季就会易感染流感。
结论/建议：南半球和北半球流感季节性差异对旅行者流感疫苗接种的有效性有重大影响。当患者报告旅行计划时，医疗保健提供者应了解流感活动情况，并提供关于预防、诊断和治疗选择的警报和建议。为了降低与旅行相关的流感风险，干预措施包括用于自我治疗的抗病毒药物（结合使用快速自我检测）、延长流感疫苗的保质期，以便国际旅行者在夏季进行免疫接种，并允许使用相反半球的流感疫苗作为旅行相关疫苗。有了目前可用的疫苗，最重要的预防措施是优化季节性流感疫苗接种。同样重要的是，旅行者和医疗保健专业人员都应将流感视为与旅行相关的疾病。
