NHS West Kent, the primary care trust for north Kent, has answered questions on the swine flu vaccination for pregnant women to allay the fears of expectant mothers.

Q: Why are pregnant women in one of the priority at-risk groups for vaccination?

A: Evidence shows pregnant women are at increased risk of severe disease and flu-related hospital admissions.

The risk increases with how advanced the pregnancy is, with women in the third trimester (last three months of pregnancy) particularly at risk.

Seven to 10 per cent of all hospital admissions for swine flue are pregnant women in their second or third trimester of pregnancy, according to World Health Organisation (WHO) data.

Pregnant women are also ten times more likely to need care in an intensive care unit compared with the general population.

Q: Is the vaccine safe for pregnant women?

A: Yes. Both vaccines have been licensed for use in pregnant women.

Licensed vaccines, including flu vaccines, are held to a very high standard of safety. They simply would not be licensed if they were unsafe.

European regulators have considered the safety record of seasonal flu vaccines and the nature of the adjuvants (additional agents added to vaccines to make them more effective) that were incorporated in the pandemic vaccines.

Extensive research has also been carried out into the use of adjuvants and there is no evidence they are associated with any risks in pregnancy.

The seasonal flu vaccine has been given to millions of pregnant women at all stages of their pregnancy and has an excellent safety record, with no reported safety concerns.

This is why in the UK, and many other countries, vaccination against seasonal flu is recommended for pregnant women, whatever the stage of the pregnancy.

Q: Why is thiomersal present in the vaccine and is there any risk from it?

A: Pandemrix contains five micrograms of thiomersal (a mercury-containing compound) as a preservative.

This is added to prevent the vaccine becoming contaminated by bacteria during preparation, storage and use.

There are now numerous studies from many countries done in different ways that all come to the same conclusion: we cannot identify harm from thiomersal in vaccines.

Indeed, the US courts threw out thiomersal as a cause of autism.

One of the most compelling pieces of evidence was that when thiomersal was taken out of US childhood vaccines, autism rates continued to rise.

The minute quantities of thiomersal in vaccines have been shown not to be harmful.

Q: What is an adjuvant?

A: An adjuvant is a compound that can be added to a vaccine to enhance the immune response to the vaccine.

The use of an adjuvant can also reduce the amount of antigen (the active substance that causes your immune system to produce antibodies) that is needed to produce a satisfactory immune response, which in turn, makes the vaccine safer.

People understandably want to know what is in the adjuvant. It contains a fish oil (squalene) and vitamin E, both naturally occurring products we have in our bodies.

There is also a substance called Polysorbate 80 that is a food additive and is in many medicines.

The use of adjuvanted vaccines in pregnant women has raised concerns.

Q: Why are pregnant women advised to take Pandremix?

A: We know that in healthy adults one dose of Pandemrix protects almost everybody with very high levels of antibodies.

With Celvapan, the proportion of people who will be protected after one dose is considerably fewer.

For this reason, the European Commission still recommends two doses of Celvapan.

At a time when H1N1 viruses are circulating it has to be better for everybody to be protected after one dose than fewer and with lower antibodies.

Pregnant women are advised to receive the adjuvanted vaccine Pandemrix as this vaccine appears to give adequate levels of antibodies after a single dose which provides protection more rapidly than would be offered by Celvapan.

As pregnant women are at increased risk of severe disease and hospitalisation, it is vital they are protected as soon as possible from swine flu infection.

However, some pregnant women have requested they would prefer Celvapan as it contains no adjuvants.

On November 19, the Department of Health updated guidance so this vaccine is now available to pregnant women who request it.

Q: Have the vaccines been tested on pregnant women?

A: Women who are already pregnant are generally not enrolled into clinical trials.

The safety of giving a particular vaccine to pregnant women is assessed from what is already known about the ingredients in the vaccine and the results of testing carried out to see if the vaccine poses any risk during pregnancy.

However, non-pregnant women who are enrolled into vaccine clinical trials sometimes become pregnant shortly after vaccination or are given vaccine before they know they are pregnant.

These women are followed up and the outcome of the pregnancy is documented.

Women who were, or became pregnant, during the clinical trials of the swine flu vaccine were carefully monitored and there was no evidence of any specific risk to the mother or their unborn child due to the vaccine.

Q: Can the swine flu vaccine cause flu?

A: No. The flu vaccine cannot give you flu as it does not contain a live virus.

Some people may experience mild flu-like symptoms, such as fever, headache and muscle aches, for up to 48 hours after immunisation as their immune system responds to the vaccine, but this is not flu.

Q: Are there any other side effects?

A: All vaccinations can produce side effects such as redness, soreness and swelling at the site of the injection.

The vast majority of these side effects are not serious.

If you think that you or someone you know has experienced a more serious side effect to Pandemrix or Celvapan, please speak to your GP or midwife or report it to the Medicines and Healthcare products Regulatory Agency at mhra.gov.uk/swineflu You can find out more at nhs.uk.

You can also discuss the swine flu vaccine and pregnancy with your GP, practice nurse or midwife if you have any concerns.