What is influenza? How did it originate?
Seasonal influenza, known as ‘flu’, is an common acute respiratory infection caused by influenza viruses. First arising around 6,000 years ago, these viruses are thought to have spread to humans through the domestication of animals.
Symptoms of influenza
Flu symptoms include fever (a temperature of 38C or above), headaches and muscle aches, feeling tired, a sore throat, cough, insomnia, loss of appetite, nausea, vomiting, stomach pain and diarrhoea. With flu, these symptoms often manifest very quickly and patients may even be able to remember the hour that they began feeling sick.
Children may also suffer from ear pain and be less active.
Transmission and Seasonality
Flu is caused by germs that are spread through coughs and sneezes. These germs can live on surfaces including hands for up to 24 hours.
In temperate places, flu epidemics are seasonal, occuring during the winter. In tropical areas, outbreaks can occur throughout the year.
What are the infected areas in the world?
Influenza causes illness in all parts of the world, from mild symptoms to severe illness and even death.
Most people who die from flu-related illness in industrialized countries are over 65, while research suggests that 99 percent of children under 5 who die from flu-related illnesses are in developing countries.
What is an influenza certificate?
An influenza certificate proves that you have had the flu vaccination. It is not normally a requirement for travel.
Is influenza curable?
There’s no cure for the influenza virus but the symptoms can be managed and most people will recover in around a week.
However some groups are more at risk of becoming seriously ill due to the flu virus. They include people over 65, or who are pregnant, or have a long term health condition, or a weak immune system.
The NHS recommends getting vaccinated with the flu vaccine, ideally before the flu season starts (in the UK, from December to March). The vaccine reduces the risk of catching flu, as well as spreading it to others.
You can also help prevent the spread of flu by:
- washing your hands with soap and warm water often
- drying your hands properly after washing them
- catching your cough or sneeze in a tissue, and throwing it away as quickly as possible.
- avoid touching your face, eyes or mouth with your hands
- stay away from others if you feel feverish or have other symptoms
- avoid close contact with sick people.
How long before a trip do you have to get the influenza vaccine?
You should get vaccinated at least two weeks before travel to give your body enough time to fully develop the antibodies that protect you from catching the flu.
Who should get the influenza vaccine?
Usually flu will clear up on its own after around a week. However, it can cause more serious complications including pneumonia for some groups of people, who are advised to get the flu vaccine every year.
- people aged 65 and over
- pregnant women
- children and adults with an underlying health condition, such as long-term respiratory or heart disease)
- children and adults with weakened immune systems.
Who should not get the influenza vaccine?
Most people can have the flu vaccine. However, if you’ve had a serious allergic reaction to the flu vaccine previously, you should avoid it.
The influenza vaccine is usually made by growing the vaccine in chicken eggs so small amounts of the protein may remain in the vaccine. If you have an egg allergy, you can get a version that is egg-free or has a low egg content. You should be extra cautious if your egg allergy is severe and you have previously been admitted in intensive care for a severe anaphylactic reaction to egg. You doctor will be able to advise you further.
If you have a fever you should postpone your vaccination until you have recovered.
What is the minimum age requirement for the influenza vaccine?
Children over 2 years old can get the flu vaccine, usually as a nasal spray instead of an injection. Adults usually receive the vaccine by injection.
Children aged between 6 months and 2 years old who are in a high-risk group for flu may also be given the flu vaccine by injection. You doctor or pharmacist can advise you further.
What is the effectiveness of the influenza vaccine?
The flu vaccine is the best method of protection we have against influenza. It is not guaranteed 100 percent effective, but even in the rare case you do get the flu after vaccination, you’ll likely experience milder symptoms and recover quicker than if you hadn’t been vaccinated.
Protection reduces over time and new strains of flu develop, so yearly vaccinati0ns are recommended.
What are the side effects of the influenza vaccine?
Side effects of the flu vaccine include mild fever, and muscle aches which last around a day or two.
The injection may cause a sore arm for a few days. The nasal spray given to children is painless but may cause a runny nose.
Some people think the vaccine side effects are symptoms of catching the flu, but the virus you are given is inactive. This makes it impossible to catch the flu from the flu vaccine.
Dosage and Duration
For children between 2 and 17 years old the flu vaccine is given as a nasal spray squirted once in each nostril.
Adults between 18 and 65 receive one injection of the vaccine which prevents against four strains of flu virus.
Adults over 65 receive one injection of an adjuvanted version of the vaccine, which makes the vaccine more effective for this age group.
The protection provided by the flu vaccine reduces over time, so the WHO recommends getting vaccinated every year.
When and where was the last outbreak of influenza?
Influenza outbreaks cause between 3 and 5 million severe cases of illness and between 290,000 and 650,000 deaths each year.
The last major pandemic was swine flu in 2009, caused by the flu virus known as H1N1. It was named for its similarity to a flu that affects pigs and affected mainly young people, who had less immunity to it. H1N1 is now included in the annual flu vaccine.