Flu vaccine may not be effective in older patients

The vaccination of people over 65 against influenza may be ineffective and not reduce deaths, according to a study published in The Lancet Infectious Diseases journal.

The study points out that although placebo-controlled randomised trials show the influenza vaccine is effective in younger adults, few trials have included elderly people, especially those aged at least 70 years, the age-group that accounts for three-quarters of all influenza-related deaths.

"The remaining evidence base is currently insufficient to indicate the magnitude of the mortality benefit, if any, that elderly people derive from the vaccination programme," said the study.

The evidence that is available suggests the positive clinical benefits of the vaccine declines as patients get older, especially after the age of 70.

Every year people over the age of 65 are vaccinated against influenza. But Dr Lone Simonsen and his colleagues from George Washington University, Washington DC, authors of the study, said recent mortality studies were unable to confirm a decline in influenza-related deaths since 1980, even though vaccination has increased from 15 per cent to 65 per cent.

The study also reveals that previous studies have claimed a 50 per cent reduction in the total risk of death in winter, whereas mortality studies have shown only around five per cent of winter deaths are as a result of influenza.

The researchers claim that several studies have shown selection bias and chose stronger, healthier patients to give a better impression of vaccine benefits.