Swine flu: key facts

What is H1N1 (swine flu)?

H1N1 is a new strain of the influenza virus, commonly known as swine flu. The virus was first identified in Mexico in April 2009. It has since become a global pandemic. It is expected that there will be more cases of swine flu during the UK's winter flu season and it is also possible that the virus will change over time and become stronger.

It has spread quickly because it is a new type of flu virus that few, if any, people have full resistance to. Unlike seasonal flu, children and young adults are at higher risk than older people (over 65) of getting swine flu, as are those with some underlying conditions.

In most cases the virus has proved relatively mild. However, some people have become more seriously ill and some have died, including some previously healthy people. The most common complications have been bacterial chest infections such as pneumonias.

How is swine flu spread?

H1N1 is very contagious and spreads from one person to another in small droplets of saliva when someone with swine flu coughs or sneezes  – the same way as colds and ordinary flu are spread. The virus can live on a hard surface for 24 hours and on a soft one for about 20 minutes. People can be infected through the droplets left by an infected person on objects such as phones, keyboards and door handles.

The incubation period is usually between two and five days but can be up to seven. People are most infectious soon after they develop symptoms and are not considered infectious anymore once their symptoms have disappeared.

Can I avoid swine flu?

There’s no indication at the moment that you should be doing (or not doing) anything drastic to avoid catching it. Unless you have symptoms of swine flu, you can carry on with your daily life. Cleaning your hands – either by washing them with soap and warm water or by using alcohol-based gels – after touching hard surfaces that are handled by other people may help you avoid infection.

Using face masks to prevent infection isn’t recommended for the general population.

Swine flu and HIV

There’s little specific information on swine flu and HIV so far. HIV-positive people do not seem to be at higher risk of getting swine flu. Some research has shown that generally HIV doesn't seem to affect the severity or outcome of having swine flu, although having a low CD4 cell count (under 200) can increase the risk of complications. Having a condition such as asthma or TB as well can increase the risk further, especially as complications are most often chest infections such as bronchitis or pneumonia. 

Can I prepare for swine flu?

If you do have a low CD4 count or have an AIDS-defining illness, it would be a good idea to check with your HIV clinic whether you could be taking any action to reduce risk.

If you are on HIV treatment, you should ensure you have enough supplies of your anti-HIV drugs (see Visiting your HIV clinic below).

Preparations suggested for everyone include:

• having a thermometer and supplies of paracetamol or other cold and flu remedies
• finding a ‘flu friend’ – someone who can collect antiviral drugs or other supplies for you if necessary so you don’t have to leave home
• knowing your NHS number in case you need to get treatment – not essential but helpful.

What are the symptoms of swine flu?

The symptoms of swine flu are similar to the symptoms of regular seasonal flu. People usually have a fever or high temperature (over 38°C or 100.4°F) and two or more of the following symptoms: unusual tiredness; headache; runny nose; sore throat; shortness of breath or cough; loss of appetite; aching muscles; diarrhoea or vomiting.

There is information on what you should do if you think you have swine flu in the factsheet Swine flu: dealing with infection.

Should I take antiviral medication to protect me against swine flu?

Swine flu can be treated with the antiviral medicines oseltamavir (Tamiflu) and zanamivir (Relenza). At the moment, people with HIV are entitled to receive Tamiflu as a preventive measure. You may want to take it if you have been in close and prolonged contact with someone who has swine flu (for example, someone you live with), but you need to do this very soon after exposure. You will need to contact your GP to get a prescription. If you don't have a GP, you can find one here. Visit the Pandemic Flu website to find your nearest antiviral collection point.

The H1N1 vaccine

A vaccine has been developed against the H1N1 virus. It is given in two injections, at least three weeks apart.

The UK has a swine flu vaccination programme. First priority are people aged between six months and 65 years in the seasonal flu ‘at-risk’ groups. This includes people with HIV. The vaccine is voluntary but people in at-risk groups are advised to have it. 

The vaccine is only be available at GP surgeries. You will need to be registered with a GP, and to have told them of your HIV status.

There is not a lot of information on how well the vaccine will work in people with HIV (or whether it will cause any problems or interact with anti-HIV drugs), but some research has shown that it is safe for people with HIV. It is the same sort of vaccine as a seasonal flu one (so doesn’t have ‘live’ virus in it). Medical advice is that the benefits of having it outweigh any potential risks.

Although there is little research on the effectiveness of flu vaccines in people with HIV, one study has shown a high level of effectiveness in people with HIV. However, some research suggests that the H1N1 vaccine is not as effective in people with HIV.

Your GP should take into account other drugs you are taking that may interact with the flu vaccine. You can check for any reported interactions between the flu vaccine and anti-HIV drugs at http://www.hiv-druginteractions.org.

Visiting your HIV clinic

It’s possible that, if the numbers of people with swine flu go up dramatically at any stage, services at HIV clinics may be disrupted – or that you will be advised not to come in because of the risk of becoming infected yourself. Or you may be unwell and be unable to attend an appointment.

If you are on treatment, you should make sure you have enough supplies of your anti-HIV drugs to see you through – at least one month’s supply at any time. You could talk to your clinic about extra supplies at your next appointment.

There is more information on swine flu on the NHS Choices website at http://www.nhs.uk/Conditions/Pandemic-flu/Pages/Introduction.aspx.

We will be reporting on any new information on swine flu and HIV as it becomes available on aidsmap. Sign up to our email bulletins to be kept informed of new developments.