Winter is fast approaching; the days are becoming shorter and the nights longer. And with it, the flu season is making its comeback. It is often thought that an aircraft’s ventilation system makes you more prone to picking up the flu. However, this is not quite the case. On launching the flu jab this year, several questions regarding the flu reached me, as a doctor, at KLM Health Services:
1. What causes the flu?
Influenza (commonly known as the flu) is a viral infection of the respiratory system caused by influenza viruses. In the northern hemisphere, the peak period for the flu is from November to March. In the southern hemisphere, the peak period is from May to September.
The most common symptoms are:
– Acute onset of symptoms
– Upper respiratory infection (a cold, muscle ache, headache, fatigue and general illness).
Infection is usually through the respiratory system (droplets containing the virus carried by air or aerogenic transmission). Very few droplets containing the virus are needed for someone to become ill. Infection through direct contact (kissing and shaking hands) is also possible, but then more viruses are needed to actually become ill, aside from survival of the virus outside the body. It takes one to five days to actually becoming ill after being infected with the virus.
The survival of the virus also depends on humidity, temperature and UV radiation (sunlight). The virus survives its best under cold and dry conditions, such as in winter. Sunlight makes the virus become inactive. This explains why you are more susceptible to the flu during the winter season, when it is colder and less sunny. And besides that you tend to spend time indoor and closer to one another. You can read more about the flu here.
2. Do you catch flu quicker because of an aircraft’s ventilation system?
Air circulation in an aircraft takes place vertically, from top (the passengers’ heads) to bottom (leaving through openings at floor level) and not from front to back as often thought.
Source: IATA Medical Manual 2018
The air is refreshed every two to three minutes. Half of the air in an aircraft comes from the outside. This air is specially filtered. The other half of the air in the cabin is reused after being thoroughly filtered. Carbon dioxide (CO2) and microorganisms such as bacteria are then removed via this filter system. The air on board an aircraft is generally much cleaner than the air in buildings or in public transport on the ground.
However, the air in an aircraft is very dry. When humidity is low, the mucus of your nose and throat may become dry, and your immune system can be less effective at those points. We then become more prone to bacteria and viruses. Make sure you stay hydrated!
Catching the flu on board is therefore not directly related to the air circulation. Sitting close to one another can contribute towards catching the flu. The risk is not higher than in other forms of public transport and other public areas on the ground.
Be sure to take the necessary precautions:
– Wash your hands frequently
– Drink sufficiently (not containing alcohol and caffeine)
– Use paper tissues
– Avoid touching your nose and mouth as far as possible
3. The flu jab
In each hemisphere, each year the influenza vaccine is composed based on the most recent epidemiological data from the WHO. Shortly before the flu season starts, the vaccine becomes available. Both the northern and southern hemisphere differ in the composition of the vaccine.
In the Netherlands, certain medical risk groups (including the over-65s and anyone with a serious long-term health condition) are advised to take the vaccination.
If you are a frequent (business) traveller, you may consider taking the flu jab. Again not because of the air quality on the plane. It is true that as a frequent traveller, you may be exposed more frequently to a broader range of viruses, including influenza viruses. Sleep deprivation caused by jetlag, environmental temperature changes, different climates, other kinds of food and possibly stress, asks a lot of your own immune system. For this reason, I would advise you to take the vaccination to prevent complications of the flu. The flu jab is also available at our Travel Clinics.
Take good care of yourself and prevent the flu.