The NHS in England has been warned to prepare for a busy winter following a “heavy” flu season in Australia and New Zealand.

Here are some questions answered by Andrew Easton, professor of virology at the University of Warwick.

Why has there been a bad flu season in the Southern Hemisphere?

The reasons for the high incidence of flu in Australia are not yet clear. Flu is notoriously difficult to predict and many factors play a role. Historically the incidence of flu changes a lot from year to year so while there is some concern at the high levels seen in Australia it is not possible to say definitively why it has occurred. One factor that is being investigated is the level of vaccine uptake in the population: if that is lower than usual it may be a factor – but it would only be one factor.

Has anyone in particular been affected?

Elderly man
The elderly are among one of the groups vulnerable to flu ( Joe Giddens/PA)

Flu is a serious disease but represents a particular risk for certain groups of people. These are the elderly and anyone with an additional predisposing condition such as severe asthma or other respiratory complaint – these individuals can be of any age. There is no suggestion at the moment that one particular group has been affected more than might be seen in any annual outbreak.

Are there any indications that the vaccine has not worked as it should?

There is no suggestion of that at the moment and people are encouraged to get a vaccination if they have not already done so.

Will the UK vaccine work?

There is no reason at the moment to believe that the vaccine will not work. However, it takes 10 days or so for the vaccine to provide protection and during that time the individual is still at risk so getting the vaccine as early as possible is important.

The precise formulation for vaccines used in the Northern and Southern hemispheres can be different and this is designed to take account of the variation in flu strains that appear in these two regions.

The World Health Organisation operates a surveillance programme to detect what strains are most likely to be around and vaccine manufacturers follow this advice for their products. The current vaccine contains material to protect against the two most prevalent influenza A and the two most prevalent influenza B strains most likely to be around in the winter. Occasionally the circulating strains have been found to differ a bit from those predicted but that is not frequent and there is always some level of protection provided.

Why does a bad flu season in Australia and New Zealand mean that there will be one in the UK?

Sydney
Sydney, Australia (Steve Parsons/PA)

It does not. However the surveillance programme picks up these unusually high levels and they are taken as a warning that the particular strains around may represent a greater challenge than normal. However, as indicated, it is extremely difficult to predict the nature of a future flu season in terms of severity and so this is at the moment a “heads up” and not a prediction.

What can people do to prepare?

The key thing is that people should be made aware of any issues with flu if it develops. Those particularly at risk of severe disease should seek advice about receiving a vaccination.

What can hospitals do to prepare?

Hospital
(Peter Byrne/PA)

The main effect will not be seen at the hospital level but in the community. Hospitals will have their normal procedures in place to offer vaccine to staff to help ensure that they are not affected and will ensure that their facilities will be in good shape to address any issue. However, as the incidence of flu is detected when it appears in the UK winter it will become clearer what the true situation is and what steps will be needed to reduce the impact.