Completed Project: SIVE II

Seasonal Influenza Vaccine Effectiveness II

An evaluation of the seasonal influenza vaccine using routine data sources.

How effective is the flu vaccine?

Globally, it is estimated that seasonal influenza is responsible for five million cases of severe illness and 500,000 deaths per year, in particular older adults aged 65 and over and people with underlying diseases such as asthma.

National influenza vaccination strategies using primary care represent a potentially important approach to reduce both influenza-related illness and death, hence the considerable investment in this preventive approach in many parts of the world.

However, the evaluation of changes to immunisation programmes can be problematic given that randomised controlled trials of the vaccine are impractical and also viewed as unethical by some sections of the medical community. Policy changes therefore typically go unevaluated, making it difficult to inform ongoing policy deliberations.

The facts

The flu vaccine is effective in preventing flu in healthy people (when well matched).
We don’t know how effective it is in vulnerable people (e.g. those with asthma).
We need more evidence about the new nasal flu vaccine given to children.

What are we doing about it?

Building on our substantial track-record of evaluating vaccine programmes using linked healthcare electronic record-derived information, we will conduct an evaluation of the live attenuated influenza vaccine, offered to all children aged 2-17 in Scotland.

We will recruit 500 general practices in Scotland.

We wish to determine:

the uptake of seasonal influenza vaccine by the relevant at risk populations
the reduction in the expected incidence of influenza related serious morbidity and mortality in these at risk groups
whether the new nasal vaccine confers any indirect or herd immunity
whether there are any adverse events associated with the vaccine.