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Anaphylaxis after vaccination rare

Review finds no cases reported with vaccines in pre-school or infant schedule

Ingrid Torjesen

Tuesday, 24 January 2012

It is extremely rare for patients to experience anaphylactic shock following vaccination, research published online in the Archives of Disease in Childhood has found.

Only seven cases were confirmed in the UK and Ireland between 2008 and 2009, and none of them were related to vaccines in the pre-school or infant vaccination schedule.

Anaphylaxis is a rare extreme reaction which can be triggered by several factors including drugs/vaccines, but it is usually very difficult to pick up as potential side effect of a new treatment during clinical trials because it is so rare. As a result manufacturers have to rely on post-marketing data.

The researchers reviewed data on children under the age of 16 in the UK and Ireland reported by specialists to the British Paediatric Surveillance Unit between 2008 and 2009 because of suspected anaphylactic shock after vaccination.

Fifteen cases were reported and these followed several types of vaccination, including the single measles jab, the HPV jab against cervical cancer, two types of vaccine for meningitis, a hepatitis A vaccine; typhoid vaccine, and a school leaver’s booster jab (probably tetanus/polio).

Only seven of these cases were confirmed as anaphylaxis and all made a full recovery. Six children required an injection of adrenaline and intravenous fluids and one child recovered without treatment. Three of the children already carried injectable adrenaline.

The single component measles vaccine was associated with two cases of anaphylaxis. As more than 16,000 doses were imported over the study period, the researchers calculated that this equated to an incidence of 12 cases of anaphylaxis per 100,000 doses.

Three cases were associated with the HPV vaccine, but as more than two million doses of this vaccine had been administered during the study period, this was equivalent to an incidence of just 1.4 cases per million doses.

Although around 5.5 million children received routine pre-school or infant vaccinations during the study period, no cases were associated with any of these vaccines, including the triple MMR jab.

Dr Mich Lajeunesse, from The Children’s Allergy Clinic at the University Hospital Southampton NHS Foundation Trust said this was “extremely reassuring”.

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