There is only ‘weakly supportive evidence’ that the switch from targeting risk groups, to immunising all those aged over 65 years against influenza, had any positive impact on mortality rates, say UK researchers.
The study looked at deaths of patients over the age of 65 years registered to underlying pneumonia and influenza in England and Wales between 1975 and 2005. Excess mortality was estimated using time series of deaths registered to pneumonia or influenza, accounting for seasonality, trend and artefacts. The research was to establish the impact on mortality of the switch from risk-based to age-based targeting of the yearly influenza vaccination in elderly patients in England and Wales, which was phased in from 1998/1999 and which resulted in a marked increase in yearly vaccine coverage.
Excess mortality for the 65 to 74 years age group ranged from zero to 2,000 deaths per influenza year in the study period. For the 75+ years age group, the range was from zero to over 14,000 deaths/influenza-year. For neither age group was there a turning point in the trend in excess mortality coinciding with the 2000/2001 season, when the policy of targeting all people aged 65+ years for yearly influenza vaccination was introduced. Similarly, there was no turning point in the trend in excess mortality in the 75+ years age group during 1998/1999 when this group became fully targeted for yearly influenza vaccination. There were fewer excess deaths, on average, in the seasons after the policy change than before.
What this means for GPs
The researchers note that there is ‘weakly supportive evidence’ that the switch from risk-based to age group-based targeting of influenza vaccination for older people was associated with a lower influenza-related mortality.