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Is the swine flu vaccine safe?

European and UK regulators have based their approval for the new vaccine, on the safety profile of the old Bird flu vaccine (H5N1) vaccine and on early preliminary data for Pandemrix® H1N1 (swine flu) vaccine. Though we don't have data for long term side effects, except for differences in the type of flu covered, the new vaccine should have a very similar safety profile to most flu vaccines.

Short-term side effects for the new Pandemrix® H1N1 vaccine are similar to the old Pandemrix® H5N1 vaccine. These side effects include redness, soreness and swelling at the site of injection. The vaccine is also likely to cause fever, headache and muscle aches, though these should only last a day or two.

The safety of the Celvapan® vaccine (another swine flu vaccine) has also been assessed on the safety profile of an old influenza vaccine containing the wild type H5N1 virus strain.

What are adjuvants and are they safe?

There have been concerns raised regarding the use of adjuvants; these are various compounds included in the vaccine which are aimed at boosting the host's immune response to the vaccine. Use of adjuvants also means less of the viral antigen (bits of the swine flu virus) has to be used per vaccine. This allows manufactures to produce more vaccines.

Pandemrix® contains adjuvant AS03, this is composed of 3 main components, squalene, Vitamin E and polysorbate 80. Squalene is a natrually occuring substance mannufactued in the liver, in this case it is taken from purified fish oil. It has been used in the Fluad® vaccine (seasonal flu vaccine) since 1997. Polysorbate 80 is an agent used widely in cosmetics, food products and pharmaceuticals including injections.

Adjuvants have been used in vaccines for decades (since the 1930s) and are still used both in Europe and America in most childhood vaccines. The UK and European regulatory bodies have approved the use of adjuvants in the H1N1 vaccine. In the United States they only permit the use of aluminium salts as adjuvants in vaccines. The seasonal flu vaccines in America however, do not contain adjuvants and it is currently unclear as to whether the American swine flu vaccine will contain adjuvants.

What is Thiomersal?

Thiomersal (also known as Thimerosal) is a mercury based preservative used in vaccines to prevent bacterial and or fungal contamination. This is likely to be used in vaccine preparations where multiple doses will be required from the same vial. It has been used for decades in America. However, new childhood vaccines in America do not contain this preservative, though its removal was precautionary rather than concerns over any reported ill effects.

Thiomersal has been claimed to be linked to cases of autism, however there is no obvious scientific evidence to corroborate this and even since its removal in childhood vaccines in America, there have been no reduction in the cases of autism, again suggesting no linkage.

What is Guillain-Barré syndrome (GBS) and its link to the new vaccines?

GBS is a rare neurological condition causing weakness and pain in the limbs and occasionally breathing difficulties. It is thought to be caused by our own immune system attacking our nervous system. The trigger is thought to be viral and or bacterial. In 60% of cases there is a history of a recent viral infection or diarrheal illness preceding the onset of the neurological symptoms by about 3 weeks. In some rare cases this condition has occurred following administration of certain vaccines.

The natural rate of occurrence of this condition is thought to be about 1 in 100,000, however 2 studies carried out in America suggested that the seasonal flu vaccine did increase this by 1 additional case per 100,000 people. Though, this was not the case with every annual flu vaccine.

In one episode of swine flu in America back in 1976 there was a slight increase in the occurrence of GBS after vaccination and was thought to be due to the then used swine flu vaccine. The over all significance of this is minimal and healthcare professionals will be monitoring cases of GBS closely. As of yet there is no evidence to suggest that the current swine flu vaccines have caused an increase in the incidence of GBS.

Does the seasonal flu vaccine cover swine flu?

No, the seasonal flu vaccine does not cover the swine flu virus (H1N1). To protect yourself from both, you will require both vaccines.

I'm allergic to egg can I still have the vaccine?

There are currently two vaccines available, Pandemrix® and Celvapan®. The Pandemrix® vaccine, normally will onlyl require one dose. It is prepared using hens' eggs. Celvapan® is the vaccine that can be given to patients with an egg allergy. This vaccine requires two to three doses.

Who will get the vaccine first?

In the UK, the vaccine has been prioritised to those groups who are more likely to be adversely affected by the swine flu (H1N1) virus. The order of priority is as follows:

Those under 65 with chronic disease affecting the lungs, kidneys, liver, heart, neurological diseases and diabetes.
Pregnant women (at any stage of pregnancy)
People who live in the same house as someone whose immune system is compromised by disease or treatment.
People aged over 65, who are currently in the at risk group for seasonal flu.

I'm not in the priority group, what do I do?

The UK government has ordered enough vaccine for all UK citizens, however current risk assessments suggest vaccination is best targeted at vunerable groups first. If however the infection becomes widespread, this will likely cause a shift in policy towards vaccinating everyone.

If I have already had swine flu, do I still need the swine flu vaccine?

If you have had swine flu, which was confirmed by serological blood tests, then you would not need the vaccine. However, if you were given treatment on the basis of symptoms, and the diagnosis was not confirmed with blood or swab tests, then there is a good chance you may not of actually had swine flu. Therefore it would be important to still get vaccinated.

References:

GlaxoSmithKline , 2009. Pandemic (H1N1) 2009 Influenza Update: Results from second clinical trial of GSK’s H1N1 adjuvanted vaccine confirm immune response and tolerability. London, UK: GlaxoSmithKline. Available from http://www.gsk.com/media/pressreleases/2009/2009_pressrelease_10111.htm [Accessed October 23rd, 2009].

GlaxoSmithKline, 2009. Pandemic (H1N1) 2009 Influenza Update: GSK’s H1N1 ‘Pandemrix’ vaccine receives positive opinion from European Regulators. London, UK: GlaxoSmithKline. Available from http://us.gsk.com/html/media-news/pressreleases/2009/2009_pressrelease_10088.htm [Accessed October 23rd, 2009].

The Committee for Medicinal Products for Human Use, 2009. Assessment report for Celvapan. London, UK: European Medicines Agency. Available from http://www.emea.europa.eu/humandocs/PDFs/EPAR/celvapan/Celvapan-H-982-PU-02-AR.pdf [Accessed October 23rd, 2009].

Department of Health circular, November 2009. Gatewat reference: 12902. Swine flu vaccination programme: Information to support the vaccination of pregnant women. London UK: Department of Health.

NHS Choices, 2009. Swine flu the latest from the NHS. London, UK: NHS Choices. Available from http://www.nhs.uk/news/2009/04April/Pages/Swineflulatest.aspx [Accessed October 24th, 2009].

Centre for disease control and prevention, 2009. Vaccine safety. Atlanta USA: CDC. Available from: http://www.cdc.gov/h1n1flu/vaccination/vaccine_safety.htm [Accessed October 29th 2009]

Dr Shazan Chughtai MB BS

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