ANALYSIS:Swine flu jab concerns are revolving around the use of adjuvants, writes DR MUIRIS HOUSTON
THE CONTROVERSY around swine flu vaccine safety in Germany is unsurprising, given the “newness” of both the Pandemic (H1N1) 2009 virus and the necessarily rushed nature of vaccine production. However, no new scientific evidence has been produced to back up these concerns and the controversy appears to centre around the purchase of different vaccines to be given to Government employees and the general public.
Ever since the unwarranted scare about MMR vaccine and autism, which was based on false concerns about thiomersal, a mercury containing compound used as a vaccine preservative, public sensitivity to “new” vaccines has been heightened.
In this case, the concerns revolve around the use of adjuvants. These are substances used to boost the effectiveness of vaccines. Derived from the Latin “adjuvans”, meaning “to help”, adjuvants have been used for many years in different vaccines. In influenza vaccines they can reduce the dose of virus needed to produce the same protective response and improve their ability to provide longer-lasting protection. Adjuvants work by prolonging the exposure time of antigen (virus) to the immune system and by providing key signals that maximise the body’s immune response. Squalene, the adjuvant contained in Pandemrix, one of the vaccines due to be used in Germany (and one of two vaccines purchased by the HSE for use here) is both a natural intermediate product of human cholesterol metabolism and a component of human cell membranes. It is also found in fish liver oil and vegetable oil.
The squalene for vaccine production is isolated from shark liver. There is already a large body of experience from its use in vaccines for humans, with no significant safety concerns raised in more than 70 clinical trials.
A minor concern is the finding that squalene-based adjuvants have been shown to induce more local reactions (pain and bruising at the injection site) within three days of vaccination than vaccines without the additive. There is also an increased risk of a systemic response but no major reactions have been reported.
A clear advantage to the use of an adjuvant in Pandemrix is the likelihood that it will mean just one shot will be needed for most people receiving the swine flu vaccine. And for those who wish to choose an alternative, a second vaccine, Celvapan, will be available in the Republic.
The controversy in Germany may have more to do with the optics of political decision-making surrounding vaccine purchase than any real scientific issues. For those with underlying medical conditions that render swine flu infection more dangerous, the risk–benefit ratio appears to strongly favour immunisation.