Risk groups for severe influenza
The influenza risk groups include people who are more likely than others to develop severe disease, should they be infected. The most recent published ECDC review indicated strong evidence for immunising two large risk groups:
- Older adults
- All persons (over six months of age) with chronic medical conditions
There is no sharp cut-off age for older adults and though a survey conducted by the Vaccine European New Integrated Collaboration Effort network (VENICE III) shows that many countries use the age of 65 years as a threshold, while other countries use younger ages.
The list of chronic medical conditions in patients often recommended for vaccination in EU/EEA Member States include diseases affecting the:
- respiratory system e.g. asthma
- cardiovascular system e.g. coronary artery disease
- endocrine system e.g. diabetes
- hepatic system e.g. liver cirrhosis
- renal system e.g. chronic renal failure
- neurological/neuromuscular conditions e.g. parkinsonism
In addition to the above:
- any condition compromising respiratory functions e.g. morbid obesity (BMI > 40), physical handicap in children and adults
- immunosuppression due to disease or treatment including due to haematological conditions and HIV infection.
In May 2012, WHO SAGE (Strategic Advisory Group of Experts on immunization) delivered its opinion on seasonal influenza immunisation and published a new Position paper on the use of influenza vaccines in the Weekly Epidemiological Record. This was supported by a background paper that announced a change from the WHO 2005 guidance in declaring a new group, pregnant women, the priority for immunisation above all other groups.
It also added young children to the groups that should be offered immunisation, emphasizing at the same time the importance of immunising the groups mentioned in the 2005 guidance: older people, individuals >6 months of age with chronic conditions, and health care workers with patient contact.
The evidence for and against immunizing pregnant women and children was summarised by ECDC in 2012 in a technical report ECDC scientific advice on seasonal influenza vaccination of children and pregnant women and the issue of pregnant women was discussed in an ECDC Scientific Advance in November 2012.