Swine flu is the common name given to a relatively new strain of influenza (flu) that caused a flu pandemic in 2009-2010.

It is also referred to as H1N1 influenza (because it is the H1N1 strain of virus).

From now on, these pages will refer to the illness as H1N1 flu.

Current status

On 10 August 2010, the World Health Organization (WHO) declared that the H1N1 influenza pandemic was officially over.

However, it is important not to ignore H1N1 flu.

The H1N1 flu virus will be one of the main viruses circulating this winter. Therefore, the H1N1 flu virus has been included in the 2010-11 seasonal flu vaccine.

Vaccination

It is recommended that people in high-risk groups be vaccinated against H1N1 (swine flu). This includes all pregnant women, at any stage of pregnancy.

Pregnant women in high-risk groups and those not in high-risk groups are advised to take the seasonal flu jab, which protects against H1N1 flu.

This is because there is good evidence that all pregnant women are at increased risk from complications if they catch H1N1 flu. For more information, see Advice for pregnant women.

Until now, only pregnant women in high-risk groups were advised to take the seasonal flu vaccine. For general information about flu, see the Health A-Z topics about Seasonal flu and the Seasonal flu jab. 

What to do if you have H1N1 flu

People with H1N1 flu typically have a fever or high temperature (over 38C or 100.4F) and may also have aching muscles, sore throat or a dry cough (see Symptoms of swine flu). The symptoms are very similar to other types of seasonal flu. Most people recover within a week, even without special treatment.

If you think you have H1N1 flu and are worried, contact your GP. They will decide the most appropriate action to take.

The National Pandemic Flu Service no longer operates.

High-risk groups 

Some people are more at risk of complications if they catch flu. People are particularly vulnerable if they have:

• chronic (long-term) lung disease
• chronic heart disease
• chronic kidney disease
• chronic liver disease
• chronic neurological disease (neurological disorders include motor neurone disease, multiple sclerosis and Parkinson's disease)
• immunosuppression (whether caused by disease or treatment)
• diabetes mellitus

Also at risk are:

• patients who have had drug treatment for asthma in the past three years
• pregnant women
• people aged 65 and over

See H1N1 flu - Prevention for a full list of people advised to have this year's flu jab.

To stop the virus spreading

The most important way to stop flu spreading is to have good respiratory and hand hygiene. This means sneezing into a tissue and quickly putting it in a bin. Wash your hands and work surfaces regularly and thoroughly to kill the virus.

Anyone who is concerned about flu symptoms should contact their GP, who will determine the most appropriate action to take.

Epidemic

An epidemic is a sudden outbreak of disease that spreads through a population in a short amount of time.

The H1N1 flu virus is spread in exactly the same way as ordinary cold and flu viruses.

The virus is contained in the millions of tiny droplets that come out of the nose and mouth when someone coughs or sneezes.

These droplets typically spread about 1 metre (3 feet). They hang suspended in the air for a while, but then land on surfaces, where the virus can survive for up to 24 hours.

Anyone who touches these surfaces can spread the virus by touching anything else.

Everyday items at home and in public places may have traces of the virus. These include food, door handles, remote controls, hand rails and computer keyboards.

People usually become infected by picking up the virus on their hands from contaminated objects and then placing their hands near their mouth or nose. It is also possible to breathe in the virus if it is suspended in airborne droplets.

Good hygiene

Preventing the spread of germs is the most effective way to slow the spread of diseases such as swine flu:

• Ensure everyone washes their hands regularly with soap and water.
• Clean surfaces regularly to get rid of germs.
• Use tissues to cover your mouth and nose when you cough or sneeze.
• Put used tissues in a bin as soon as possible.

If you or a member of your family has a fever or high temperature (over 38C/100.4F) and two or more of the following symptoms, you may have H1N1 flu:

• unusual tiredness 
• headache
• runny nose
• sore throat
• shortness of breath or cough
• loss of appetite 
• aching muscles
• diarrhoea or vomiting

It makes sense to have a working thermometer at home, as an increase in temperature is one of the main symptoms. If you are unsure how to use a thermometer, go to How to take someone's temperature.

What to do

If you have flu-like symptoms, stay at home, get plenty of rest and use over-the-counter painkillers to relieve symptoms. If you are concerned, contact your GP, who will determine the most appropriate action to take.

High-risk groups

For most people, H1N1 flu is a mild illness. Some people get better by staying in bed, drinking plenty of water and taking over-the-counter flu medication.

However, some groups of people are more at risk of serious illness if they catch flu.

It is already known that you are particularly at risk if you have:

• chronic (long-term) lung disease
• chronic heart disease
• chronic kidney disease
• chronic liver disease
• chronic neurological disease (neurological disorders include chronic fatigue syndrome, multiple sclerosis and Parkinson's disease)
• immunosuppression (whether caused by disease or treatment)
• diabetes mellitus

Also at risk are: 

• patients who have had drug treatment for asthma within the past three years
• pregnant women
• people aged 65 and older

Outlook

For most people, the illness appears to be mild. 

For a minority of people, the virus can cause severe illness. In many of these cases, other factors contribute to the severity of the illness. 

When complications occur, they are usually caused by the virus affecting the lungs. Infections such as pneumonia can develop.

Paracetamol

As with ordinary flu, people who have H1N1 flu should get lots of rest and use standard paracetamol-based cold remedies to reduce their temperature and help relieve symptoms.

Some over-the-counter treatments used by adults can be given to children for the relief of the symptoms. Follow the instructions that come with each medicine. However, children under 16 must not be given aspirin or ready-made flu remedies containing aspirin. Always read the label or check with the pharmacist that a medicine is suitable for children.

Antivirals

The antiviral medications oseltamivir (Tamiflu) and zanamivir (Relenza) may be used to treat some people with H1N1 flu. Your GP will decide if these are necessary.

Antivirals are not a cure for H1N1 flu, but will help:

• reduce the length of time you are ill by around one day
• relieve some of the symptoms
• reduce the potential for serious complications such as pneumonia

Tamiflu and Relenza are both medicines of the same type, but Relenza comes as an inhaler (rather than a pill) and is recommended for use in pregnancy.

If you are prescribed antivirals, you will need to pay a prescription charge (unless your prescriptions are normally free of charge).

Antibiotics

Antibiotics are used to treat H1N1 flu patients who develop complications. They help combat bacterial infections such as pneumonia.

In hospitals, antibiotics will be used to treat the most ill patients and may reduce the length of hospitalisation.

This page explains why pregnant women are at greater risk from H1N1 flu, what those risks are, the special precautions you should take and the safety information for H1N1 flu treatments.

Why pregnant women are more at risk

In pregnancy, the immune system is naturally suppressed. This means that pregnant women are more likely to catch flu and, if they do catch it, they are more likely to develop complications (see below).

However, your immune system still functions and the risk of complications is very small. Most pregnant women will only have mild symptoms.

Symptoms and risks

If you are pregnant and you catch H1N1 flu, the symptoms should be similar to those of regular flu. You will typically have a fever or high temperature (over 38C/100.4F) and two or more of the following:

• unusual tiredness
• headache
• runny nose
• sore throat
• shortness of breath or cough
• loss of appetite
• aching muscles 
• diarrhoea or vomiting

Most pregnant women will have only mild symptoms and recover within a week. However, there is evidence from previous flu pandemics that pregnant women are more likely to develop complications.

Possible complications are:

• pneumonia (an infection of the lungs)
• difficulty breathing 
• dehydration

In pregnant women, these are more likely to happen in the second and third trimester.

If a pregnant woman develops a complication of H1N1 flu, such as pneumonia, there is a small chance this will lead to premature labour or miscarriage. There is not yet enough information to know precisely how likely these birth risks are.

It is, therefore, important to be well prepared and to take precautions against H1N1 flu.

Vaccination and pregnancy

Pregnant women are advised to take the seasonal flu jab, whatever the stage of pregnancy. This includes pregnant women not in high-risk groups.

This year's seasonal flu jab offers protection against the H1N1 (swine flu) virus, as well as other strains of flu virus.

There is no evidence that inactivated vaccines, such as the seasonal flu vaccine, will cause any harm to pregnant women or their unborn baby. Every year, the seasonal flu vaccine is given to pregnant women who are at risk of flu.

The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency has given a clear recommendation that the GlaxoSmithKline vaccine Pandemrix can be given safely to all pregnant women.

Special precautions

If you are pregnant, you can reduce your risk of infection by avoiding unnecessary travel and avoiding crowds where possible.

Pregnant women should also follow the general advice outlined in the box, top right. Good hygiene is essential.

If you think you may have H1N1 flu, call your doctor for an assessment. Your doctor will advise you what to do if they think you have flu.

Unless you have H1N1 flu symptoms, carry on attending your antenatal appointments to monitor the progress of your pregnancy.

H1N1 flu treatment

Antivirals

If you are pregnant and diagnosed with H1N1 flu, you may be given a course of antiviral drugs.

If you have an uncomplicated illness due to influenza and do not have an underlying disease, you can take either Relenza or Tamiflu. Relenza is recommended as a first choice.

Relenza is inhaled using a disk-shaped inhaler. It is recommended for pregnant women because it easily reaches the throat and lungs, where it is needed, and does not reach significant levels in the blood or placenta. Relenza should not affect your pregnancy or your growing baby.

However, Tamiflu should be offered instead of Relenza if you:

• have a condition such as asthma or chronic obstructive pulmonary disease
• have difficulty taking an inhaled antiviral
• develop a severe or complicated disease due to influenza (where you will probably be treated in hospital)

An expert group reviewed the risk of antiviral treatment in pregnancy. It is much smaller than the risk posed by the symptoms of H1N1 flu.

Some people have had wheezing or serious breathing problems when they have used Relenza. Relenza is therefore not recommended for people with asthma or chronic obstructive pulmonary disease (COPD). Other possible side effects of Relenza include headaches, diarrhoea, nausea and vomiting.

In a small number of cases, nausea is a side effect of Tamiflu.

If you take an antiviral and have side effects, see your healthcare professional to check that you are OK.

Painkillers

You can also take paracetamol to reduce fever and other symptoms. This is safe to take in pregnancy.

However, pregnant women should not take non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Nurofen).

Practising good hygiene is the single most effective way to stop the spread of diseases such as flu. You can protect yourself and your family by:

• ensuring everyone washes their hands regularly with soap and water, and
• cleaning surfaces regularly.

You can prevent a virus spreading to others by:

• always carrying tissues,
• using tissues to cover your mouth and nose when you cough and sneeze,
• binning the tissues as soon as possible, and
• washing your hands regularly.

CATCH IT. BIN IT. KILL IT. is a simple way to remember this.

Seasonal flu jab

This winter (2010-2011), the H1N1 flu virus will be one of the main strains circulating, so it has been included in this year's seasonal flu jab. It means that the vaccine will protect you from H1N1 flu, as well as other strains.

Vaccination is given free of charge to the following at-risk people, to protect them from flu:

• people with a serious medical condition (see box, right)
• people aged 65 or over
• pregnant women (see below)
• people living in a residential or nursing home
• the main carers for an elderly or disabled person whose welfare may be at risk if the carer becomes ill
• healthcare or social care professionals directly involved in patient care
• those who work in close contact with poultry, such as chickens

This winter, the seasonal flu vaccine will be extended to pregnant women not in the high-risk groups.

Usually, only pregnant women in high-risk groups are offered the seasonal flu vaccine.

For more information on flu immunisation, including background information on the vaccine and how you can get the jab, see our pages on the seasonal flu jab.

Antiviral medication

The National Institute for Health and Clinical Excellence (NICE) recommends the antiviral medicines oseltamivir and zanamivir to prevent flu if all of the following apply:

• The amount of flu virus circulating is sufficient to mean that if someone has a flu-like illness, it is likely to have been caused by this flu virus.
• The person has a certain medical condition (see box) or is over 65.
• The person has been in contact with someone with a flu-like illness and can start treatment within 36 hours (zanamivir) or within 48 hours (oseltamivir).
• The person has not been effectively protected by vaccination (see below).

People who are not effectively protected by vaccination include:

• Those who have not been vaccinated since the previous winter.
• Those who cannot be vaccinated, or who have been vaccinated but it has not taken effect yet.
• Those who have been vaccinated for a different form of flu virus.

If there is an outbreak of seasonal flu in a residential or nursing home, oseltamivir and zanamivir may be offered to people if they have been in contact with someone with confirmed flu. This is because these homes are closed places in which flu can spread quickly.

For more information, go to the NICE guidelines on antivirals to prevent influenza.