Influenza vaccine

Influenza vaccine is prepared from dead, highly purified viruses grown in hens' eggs. Each year the vaccine contains components of virus strains related to those considered most likely to be circulating during the forthcoming winter.

Influenza vaccine gives 70-80% protection against infection. In the elderly, protection against infection may be less, but immunisation has nonetheless been shown to reduce pneumonia, admissions to hospital and fatal outcomes as a result of infection with the Influenza virus.

Recommendations

The greatest problems from influenza occur among people with underlying disease, particularly long-standing lung or heart disease, and especially if they are also elderly. The Joint Committee on Vaccination and Immunisation (JCVI), which advises the UK Health Departments, recommends that those most at risk of serious illness from influenza infection are offered influenza immunisation every year. The JCVI therefore recommends that influenza immunisation is offered to:

1. Those of all ages, and especially the elderly with long-standing lung disease, including asthma, long-standing heart disease, kidney failure, disorders such as diabetes mellitus and decreased immunity due to disease or treatment e.g. those taking oral steroids.
2. Residents of nursing homes, old people homes and other long-stay facilities where rapid spread is likely to follow introduction of infection.

Routine immunisation of fit children and adults, including health care and other key workers, is not recommended. These recommendations are unchanged from last year.

Dosage

Adults - a single injection. Children aged 3 - 12 years—injection repeated 4-6 weeks later if receiving influenza vaccine for the first time. Children aged 6 months-35 months—injection repeated 4-6 weeks later if receiving influenza vaccine for the first time.

The vaccines are prepared in hens' eggs and should not be given where there is severe allergy to egg products.

Side Effects

Influenza vaccine is usually well-tolerated apart from occasional soreness at the vaccination site. In rare instances it can, however, cause:

1. Fever, malaise and muscle pain beginning 6-12 hours after immunisation and lasting up to 48 hours.
2. More rarely, immediate reactions such as allergic rashes and allergic asthma, most likely due to hypersensitivity to residual egg protein.

Influenza vaccine contains inactivated virus and cannot cause influenza. You should be aware that influenza-like illness can be caused by many respiratory viruses and that influenza vaccine will not prevent these.

Timing of influenza immunisation

Protective antibody levels may take up to 10-14 days to develop. Influenza activity is rarely significant before the middle of November, and therefore the ideal time for immunisation is October/early November. Immunity can be expected to last through the winter.

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