Seasonal flu Q&As
Published by Bupa's health information team, March 2009.
Answers to questions about seasonal flu
This section contains answers to common questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.
- How is seasonal flu different from bird flu?
- Why do you have to have the flu vaccine every year?
- How does the flu vaccine work?
- Should I stay off work if I have seasonal flu?
How is seasonal flu different from bird flu?
Avian or bird flu generally only infects birds (and sometimes pigs). Some people in parts of Asia and Egypt have caught bird flu but this doesn't usually happen.
Explanation
Avian flu is caused by a type A influenza virus and is usually only passed by close contact with birds infected with avian flu. There is some evidence that a very small number of people may have got avian flu from a person who caught it from birds or bird faeces. It hasn't been possible to find out how avian flu is passed as all the people have been exposed to the same environmental sources and have all had very close contact with birds. There is no evidence that the virus has changed and can be passed easily between people.
Seasonal influenza or flu is an illness caused by a flu virus which affects your mouth, nose, throat and chest. Flu viruses are spread from person to person in droplets in the air. Sneezing or coughing produces more droplets and helps to spread the infection. Touching infected surfaces, such as door handles or when shaking hands, and then passing the virus from the hands to the mouth, nose or eyes is another route of infection.
Further information
- Health Protection Agency
www.hpa.org.uk
Sources
- Influenza. BMJ Clinical Evidence. www.clinicalevidence.com, accessed 4 June 2008
- Map of avian flu distribution. World Health Organization (WHO). www.who.int, accessed 17 June 2008
Why do you have to have the flu vaccine every year?
The viruses that cause flu change and different strains emerge each year.
Explanation
Generally, each year, one or two new subtypes of influenza A and a new type of influenza B develop. These new subtypes are added to the vaccine every year so your body can produce the antibodies which will stop you getting flu. This is why you need to get the flu vaccine annually.
The flu virus has proteins called antigens on its surface. These antigens change as different subtypes of flu develop. You body can detect and react to these antigens if the virus enters your body. The immune system in your body will then produce proteins called antibodies. Antibodies bind to the antigens on the virus and help destroy it.
However, if you have not been infected with a particular virus before, the antibodies are produced relatively slowly. You will usually have flu symptoms and feel unwell but afterwards you won't get that subtype of flu again - your body has produced antibodies which will fight any future infection.
When you are given the flu vaccine, your immune system produces antibodies so your immune system is prepared if the virus enters your body. There are then enough antibodies to detect the flu virus and help destroy it quickly, so you don't usually get the symptoms of flu or, if you do get symptoms, they are much less severe.
Further information
- Health Protection Agency
www.hpa.org.uk
Sources
- FAQs on influenza. Health Protection Agency (HPA). www.hpa.org.uk, accessed 17 June 2008
How does the flu vaccine work?
Flu vaccines contain the different strains (types) of inactivated influenza viruses which are most likely to be passed between people in the coming year. Flu vaccines work by making your body produce antibodies against these specific flu viruses to fight infections of these virus strains. New flu vaccines are needed every year because flu viruses are continuously changing to produce new strains.
Explanation
Flu vaccines contain inactivated flu viruses, which make your body produce antibodies to fight infection. They don't cause flu because the viruses are no longer actively infectious. The antibodies your body produces allows your immune system to recognise and respond rapidly if you're exposed to 'real' flu viruses at a later date. Having the flu jab could completely prevent you from getting the flu or mean that the symptoms aren't as bad if you do get it.
After your flu jab, it usually takes 10 to 14 days for antibodies to be produced in the amount needed to protect you from flu. Flu vaccines protect between seven and eight in every 10 people against flu infection if the flu strains in the vaccine are well matched with those trying to infect you. Protection lasts for about a year. If you become infected with one strain of flu, this won't protect you against different flu strains that may infect you the following year. This means that new flu vaccines need to be produced each year to match the strains most likely to infect you.
The main types of flu vaccine available in the UK are the 'split virus' and the 'surface antigen' vaccines. These terms refer to the way the viruses have been inactivated. Flu vaccines contain inactivated viruses of two different strains of influenza A and one strain of influenza B. The flu strains that are circulating throughout the world are monitored, and the strains chosen to be in the vaccine are those most likely to be in circulation in the next flu season.
As flu vaccines are produced from viruses that are grown in eggs, you may not be able to have the flu jab if you're allergic to eggs.
Contact your GP for advice about the flu jab and if you need to have it.
Further information
- Health Protection Agency
www.hpa.org.uk
Sources
- Immunizations - influenza. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 6 May 2008
Should I stay off work if I have seasonal flu?
The Health Protection Agency advises you to rest, drink enough fluids and take the painkiller you usually take for a headache to help get better.
Explanation
The flu viruses are easily spread between people. If you have flu, it is best to stay off work and go back when you feel better. This may help you recover more quickly and help prevent you passing the virus to someone else.
Further information
- Health Protection Agency
www.hpa.org.uk
Sources
- FAQs on influenza. Health Protection Agency (HPA). www.hpa.org.uk, accessed 17 June 2008
Related topics
- Seasonal flu
- Antibiotics
- Asthma in adults
- Asthma in children
- Avian flu (bird flu)
- Common cold
- Fever in children
- Giving up smoking
- Healthy eating
- Medicines for flu
- Physical activity
- Pneumonia
This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.
Publication date: March 2009
Flu factsheet
Visit the seasonal flu health factsheet for more information.
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