From the Guidelines
Viral illnesses may increase the risk of venous thromboembolism (VTE) during long-haul flights, and preventive measures such as staying well-hydrated, performing frequent leg exercises, and wearing graduated compression stockings are advisable for travelers with active viral infections planning long flights. The combination of viral illnesses and long-haul flights represents a potentially dangerous scenario, as viral infections can trigger inflammatory responses that increase blood coagulability and endothelial dysfunction, which are key factors in thrombus formation. When combined with the known risk factors of air travel (prolonged immobility, dehydration, and hypoxia in the aircraft cabin), this inflammatory state may compound VTE risk.
Specific viruses like influenza and COVID-19 have demonstrated prothrombotic effects, with COVID-19 in particular showing significant association with thrombotic complications 1. For travelers with active viral infections planning long flights, preventive measures are advisable, including:
- Staying well-hydrated
- Performing frequent leg exercises
- Walking periodically during the flight
- Wearing graduated compression stockings
- Considering prophylactic low-molecular-weight heparin for those with additional risk factors
The timing matters as well - traveling during the acute phase of a viral illness when inflammatory markers are highest likely presents the greatest risk. If possible, postponing long-haul travel until recovery from viral illness is complete would be prudent, especially for individuals with other VTE risk factors. According to a study published in Nature Reviews Cardiology, the risk of VTE in individuals with pro-thrombotic risk factors is substantially higher than in the general population 1. Another study published in Chest suggests that frequent ambulation, calf muscle exercise, or sitting in an aisle seat if feasible can help prevent VTE in long-distance travelers at increased risk 1. Additionally, the use of properly fitted, below-knee graduated compression stockings providing 15 to 30 mm Hg of pressure at the ankle during travel is recommended for long-distance travelers at increased risk of VTE 1.
From the Research
Viral Illnesses and Venous Thromboembolism Risk
- There is no direct evidence in the provided studies that links viral illnesses to an increased risk of venous thromboembolism (VTE) in the setting of long-haul flights.
- However, the studies do discuss the risk of VTE in various settings, including long-haul flights 2, and the use of preventive measures such as graduated compression stockings 3, 4, 5 and low-molecular-weight heparin 4, 5, 6.
Preventive Measures for VTE
- Graduated compression stockings have been found to be effective in preventing VTE in certain patient populations 3, 4, 5.
- Low-molecular-weight heparin has also been shown to be effective in preventing VTE, particularly when used in combination with graduated compression stockings 4, 5, 6.
- The study by 2 found that travelers with one or more risk factors for VTE should consider graduated compression stockings and/or low-molecular-weight heparin for flights longer than 6 hours.
Risk Factors for VTE
- The study by 2 identified several risk factors for VTE, including duration of travel, clinical risk, and method of screening for VTE.
- However, viral illnesses are not mentioned as a risk factor for VTE in any of the provided studies.
Conclusion Not Applicable
As per the instructions, no conclusion section should be provided. The information provided is based on the available evidence and does not include any personal opinions or advice.