How the flu virus spreads

The H1N1 flu virus is spread in exactly the same way as ordinary colds 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 one metre (3ft). 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 on further by touching anything else.

Everyday items at home and in public places may have traces of the virus, such as food,door handles, the TV remote control, 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. You should always:

• 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, and
• put used tissues in a bin as soon as possible.

Why it spreads quickly

Evidence from previous pandemics suggests that one person will infect about two others, and that flu spreads particularly rapidly in closed communities such as schools or residential homes.

If you or a member of your family has a fever or high temperature (over 38°C/100.4°F) 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, take 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.

Paracetamol

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

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

Antivirals

The antiviral medications oseltamavir (Tamiflu) and zanamivir (Relenza) are also being used throughout the UK to treat people with H1N1 flu. Your GP will decide if these are necessary.

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

• reduce the length of time you are ill by around one day,
• relieve some of the symptoms, and

• reduce the potential for serious complications such as pneumonia.

This section 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 in high-risk groups and pregnant women not in high-risk groups are advised to take the seasonal flu jab, whatever the stage of pregnancy, which protects against H1N1 flu.

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

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 under the heading 'General measures to prevent H1N1 flu' below. 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 like 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 below)
• 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

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

As of December 2010 (the winter of 2010/11), all pregnant women who request the seasonal influenza vaccine should be offered it, irrespective of whether they have already received the H1N1 (monovalent) vaccine.

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

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 below) 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.