Combien de temps avant de voyager devriez-vous vous faire vacciner ?

In November, a British man died after contracting rabies from a cat bite while visiting Morocco. According to reports, his life could potentially have been saved had he been given a course of the rabies vaccine in time.

While rare, tragic cases such as this are a timely reminder of the importance of being vaccinated before travelling to certain countries in order to protect yourself - and others - against a range of potentially serious diseases, such as rabies, yellow fever, typhoid et hépatite A.

How do vaccinations work?

Vaccination works by introducing a small amount of inactive/weakened bacterium or virus, or inactivated toxins, into the body, either orally or by injection. Sometimes the toxin or poison made by the bacterium or virus is given to the body. These methods are known as immunisation by a vaccine as opposed to immunity you get from your mother, for instance.

Because the agent in the vaccine is inactive or weak, you cannot get an infection from it. Instead, the vaccine kick-starts the body's immune system and our white blood cells start working, helping the body make antibodies that act like soldiers to fight infections from a specific bacterium or virus.

The good news is, if the exact same bacterium or virus enters our body again, these antibodies wake up and protect us from getting sick. This memory defence system is called immunity and sometimes it can be lifelong.

The vaccines you will need depend on your destination, personal health and planned activities, while the timescales in which they need to be taken prior to travel differ for each one.

Within 7-14 days of receiving a vaccination, the body will usually develop protection to help fight infection. However, some, such as rabies or hépatite B vaccine, require multiple doses spread over several weeks to ensure adequate immunity.

"A vaccination for yellow fever, for example, is a mandatory requirement for travelling to some countries in Africa and South America," explains Lynda Bramham, travel health nurse specialist at the National Travel Health Network and Centre (NaTHNaC).

"However, the international certificate required for yellow fever does not become valid until ten days after the vaccine has been administered.

"Some vaccinations offer lifelong protection, whereas others require a booster dose after several months or years. For the flu vaccine, a dose is required every year.

"We advise those travelling outside the UK to get advice from their GP surgery or travel clinic at least 4-6 weeks before they are due to travel; those with complex medical needs should seek advice earlier."

Don't be tempted to leave getting vaccinated to the last minute as the body may not have enough time to produce antibodies, leaving you at risk of not being adequately immunised or protected.

Getting vaccines late also means if you were to develop side-effects, this could potentially happen when you are travelling or when you first get to your destination.

"It is advisable to start your vaccinations around eight weeks prior to travel, as it can take a few days to a few weeks for your body to make antibodies," states Dr Preethi Daniel from the London Doctors Clinic.

"Some people require immunisation well in advance, and some may require more than one injection in the course, so you need to allow time for this."

NaTHNaC advises those travelling outside the UK to get advice from their GP surgery or travel clinic at least 4-6 weeks before they are due to travel, while those with complex medical needs should seek advice earlier. It's probably worth going for an 8-week rather than a 4- to 6-week window, as earlier immunisation will never do any harm, whereas leaving it too late can.

However, even if time is short, it may still be worth getting advice. Some last-minute vaccinations are recommended as they may be effective before a disease with a long incubation period develops, and others may be worthwhile even if they don't provide immediate protection for the first part of your trip abroad. Other preventative measures can also be discussed.

'Immunisation Against Infectious Disease', also known as the Green Book, has the latest information on UK vaccines and vaccination procedures.

It is not uncommon for patients to develop mild, short-lived side-effects, such as myalgia (muscle pain), headache and low-grade fever, during the first five to ten days following vaccination.

Sometimes, people can also develop reactions to the ingredients that carry the vaccine, such as egg protein or gelatine, so always be sure to tell your nurse beforehand about any allergies before being vaccinated.

On very rare occasions, a severe allergic (anaphylactic) reaction may occur within a few minutes of the vaccination. Some vaccines can be contra-indicated (cannot be given) to certain individuals for medical reasons, and precautions should also be taken with some vaccines for certain risk groups - for example, pregnant women, individuals aged 60 and older, individuals living with VIH, or those whose immune system is weakened.

Without vaccination you will be unprotected with a risk of becoming infected and further transmitting the infection. Remember, vaccinations not only aim to reduce risks to the individual - they are also an important weapon in the fight to prevent transmission as part of wider disease control efforts.

"The public health risks of lack of vaccination can be separated into individual health risk (direct infection), and public health risk (onwards transmission)," Bramham confirms. "There are also associated costs to health systems if people are unvaccinated and become infected."

"While many vaccines provide high levels of protection, some are not as effective - typhoid vaccine, for example, provides around 70% protection over three years and therefore other infection prevention measures such as care with food, water and personal hygiene are important," she adds.

So, if in doubt, make an appointment with a GP surgery or travel clinic so that vaccines and other preventative measures can be discussed.