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Influenza



Influenza is a seasonal viral infection that is caused by infection with one of two viruses – Influenza A or Influenza B. In the UK it usually peaks during the winter months with the season starting a few weeks after the children return to school in September.

Although vaccines are available to help prevent infection with Influenza there are many different sub-types of the virus and therefore predicting which particular virus is going to cause most infections in a particular year is difficult. This is because the virus is made up of two major proteins; the H protein and the N protein. This is how the different strains of influenza are named, according to the types of H & N proteins that are present on the virus surface. Slight variations in the protein give rise to different types of influenza such as H1N1 or H3N2 . There are many different combinations of these 2 proteins and any vaccine that is produced has to be specific to a particular virus.

Bird flu (also known as Avian Influenza) is a form of Influenza virus that affects the bird (avian) population. It is not currently considered a threat to human populations. The H7N9 avian virus gave rise to human cases in spring 2013 in China. Although control measures have largely regulated the spread of this virus there have been approximately 800 laboratory confirmed cases since the initial outbreak in 2013, however, very few cases have been reported in children and sustained human to human transmission appears to be rare.

Swine flu arises from the H1N1 variant of the influenza virus (although there are other variants such as H3N2) and was responsible for the pandemic declared by the World health organisation between March 2009 & August 2010. This particular virus appeared to have more gastrointestinal affects compared with standard seasonal influenza.

Influenza A virus appears to have a peak transmission from infected patients at 1 – 2 days after the onset of symptoms. In contrast, Influenza B virus appears to peak in terms of transmission at 2 days before the onset of symptoms to 2 days after.

In 2015 influenza infections peaked over the months of January to February with a rapid fall in the spring months.

Influenza is transmitted by secretion droplets such as through coughing, sneezing or by direct touch.

Vaccination in children may help to prevent acquiring the disease and passing it onto others (see section on nasal spray vaccination below). Each year the nasal flu spray protects against four of the flu strains which are most likely to be around. It prevents 50% – 60% of flu cases.

The vaccine contains gelatine, used as a stabiliser. The gelatine comes from pigs, but very sensitive scientific tests have shown that no DNA from pigs can be detected in the nasal flu spray. This may however be important for some parents. (Link to vaccine information) . The vaccine also contains sucrose, potassium and monosodium glutamate. There is no thiomersal (mercury). Patients with severe egg anaphylaxis are contraindicated to receiving the vaccine but the amount of ovalbumin (egg protein) is so small that those with mild egg allergy can receive the vaccine safely at their GP surgeries.

Giving your child a vaccination can be a difficult decision for some parents, we hope that by supplying you with the information we can help you make an informed choice.

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